LibGUI: Introduce GML - a simple GUI Markup Language :^)

This patch replaces the UI-from-JSON mechanism with a more
human-friendly DSL.

The current implementation simply converts the GML into a JSON object
that can be consumed by GUI::Widget::load_from_json(). The parser is
not very helpful if you make a mistake.

The language offers a very simple way to instantiate any registered
Core::Object class by simply saying @ClassName

@GUI::Label {
    text: "Hello friends!"
    tooltip: ":^)"
}

Layouts are Core::Objects and can be assigned to the "layout" property:

@GUI::Widget {
    layout: @GUI::VerticalBoxLayout {
        spacing: 2
        margins: [8, 8, 8, 8]
    }
}

And finally, child objects are simply nested within their parent:

@GUI::Widget {
    layout: @GUI::HorizontalBoxLayout {
    }
    @GUI::Button {
        text: "OK"
    }
    @GUI::Button {
        text: "Cancel"
    }
}

This feels a *lot* more pleasant to write than the JSON we had. The fact
that no new code was being written with the JSON mechanism was pretty
telling, so let's approach this with developer convenience in mind. :^)

4 files changed, 109 insertions, 124 deletions

diff --git a/Applications/TextEditor/CMakeLists.txt b/Applications/TextEditor/CMakeLists.txt
index eadf6decfb..897a77f287 100644
--- a/Applications/TextEditor/CMakeLists.txt
+++ b/Applications/TextEditor/CMakeLists.txt
@@ -1,9 +1,9 @@
-compile_json_gui(MainWindow.json MainWindowUI.h main_window_ui_json)
+compile_gml(MainWindow.gml MainWindowGML.h main_window_gml)
 
 set(SOURCES
     main.cpp
     TextEditorWidget.cpp
-    MainWindowUI.h
+    MainWindowGML.h
 )
 
 serenity_bin(TextEditor)
diff --git a/Applications/TextEditor/MainWindow.gml b/Applications/TextEditor/MainWindow.gml
new file mode 100644
index 0000000000..d766a57e0a
--- /dev/null
+++ b/Applications/TextEditor/MainWindow.gml
@@ -0,0 +1,105 @@
+@GUI::Widget {
+    name: "main"
+    fill_with_background_color: true
+
+    layout: @GUI::VerticalBoxLayout {
+        spacing: 2
+    }
+
+    @GUI::ToolBarContainer {
+        @GUI::ToolBar {
+            name: "toolbar"
+        }
+    }
+
+    @GUI::HorizontalSplitter {
+        @GUI::TextEditor {
+            name: "editor"
+        }
+
+        @Web::OutOfProcessWebView {
+            name: "webview"
+            visible: false
+        }
+    }
+
+    @GUI::Widget {
+        name: "find_replace_widget"
+        visible: false
+        fill_with_background_color: true
+        horizontal_size_policy: "Fill"
+        vertical_size_policy: "Fixed"
+        preferred_height: 48
+
+        layout: @GUI::VerticalBoxLayout {
+            margins: [2, 2, 2, 4]
+        }
+
+        @GUI::Widget {
+            name: "find_widget"
+            fill_with_background_color: true
+            horizontal_size_policy: "Fill"
+            vertical_size_policy: "Fixed"
+            preferred_height: 22
+
+            layout: @GUI::HorizontalBoxLayout {
+            }
+
+            @GUI::Button {
+                name: "find_previous_button"
+                text: "Find previous"
+                horizontal_size_policy: "Fixed"
+                vertical_size_policy: "Fill"
+                preferred_width: 150
+            }
+
+            @GUI::Button {
+                name: "find_next_button"
+                text: "Find next"
+                horizontal_size_policy: "Fixed"
+                vertical_size_policy: "Fill"
+                preferred_width: 150
+            }
+        }
+
+        @GUI::Widget {
+            name: "replace_widget"
+            fill_with_background_color: true
+            horizontal_size_policy: "Fill"
+            vertical_size_policy: "Fixed"
+            preferred_height: 22
+
+            layout: @GUI::HorizontalBoxLayout {
+            }
+
+            @GUI::Button {
+                name: "replace_previous_button"
+                text: "Replace previous"
+                horizontal_size_policy: "Fixed"
+                vertical_size_policy: "Fill"
+                preferred_width: 100
+            }
+
+            @GUI::Button {
+                name: "replace_next_button"
+                text: "Replace next"
+                horizontal_size_policy: "Fixed"
+                vertical_size_policy: "Fill"
+                preferred_width: 100
+            }
+
+            @GUI::Button {
+                name: "replace_all_button"
+                text: "Replace all"
+                horizontal_size_policy: "Fixed"
+                vertical_size_policy: "Fill"
+                preferred_width: 100
+            }
+        }
+    }
+
+    @GUI::StatusBar {
+        name: "statusbar"
+    }
+}
+
diff --git a/Applications/TextEditor/MainWindow.json b/Applications/TextEditor/MainWindow.json
deleted file mode 100644
index 899dc1befe..0000000000
--- a/Applications/TextEditor/MainWindow.json
+++ /dev/null
@@ -1,120 +0,0 @@
-{
-    "name": "main",
-    "fill_with_background_color": true,
-
-    "layout": {
-        "class": "GUI::VerticalBoxLayout",
-        "spacing": 2
-    },
-
-    "children": [
-        {
-            "class": "GUI::ToolBarContainer",
-            "children": [
-                {
-                    "class": "GUI::ToolBar",
-                    "name": "toolbar"
-                }
-            ]
-        },
-        {
-            "class": "GUI::HorizontalSplitter",
-            "children": [
-                {
-                    "class": "GUI::TextEditor",
-                    "name": "editor"
-                },
-                {
-                    "class": "Web::OutOfProcessWebView",
-                    "name": "webview",
-                    "visible": false
-                }
-            ]
-        },
-        {
-            "class": "GUI::Widget",
-            "name": "find_replace_widget",
-            "visible": false,
-            "fill_with_background_color": true,
-            "horizontal_size_policy": "Fill",
-            "vertical_size_policy": "Fixed",
-            "preferred_height": 48,
-            "layout": {
-                "class": "GUI::VerticalBoxLayout",
-                "margins": [ 2, 2, 2, 4 ]
-            },
-            "children": [
-                {
-                    "class": "GUI::Widget",
-                    "name": "find_widget",
-                    "fill_with_background_color": true,
-                    "horizontal_size_policy": "Fill",
-                    "vertical_size_policy": "Fixed",
-                    "preferred_height": 22,
-                    "layout": {
-                        "class": "GUI::HorizontalBoxLayout"
-                    },
-                    "children": [
-                        {
-                            "class": "GUI::Button",
-                            "name": "find_previous_button",
-                            "text": "Find previous",
-                            "horizontal_size_policy": "Fixed",
-                            "vertical_size_policy": "Fill",
-                            "preferred_width": 150
-                        },
-                        {
-                            "class": "GUI::Button",
-                            "name": "find_next_button",
-                            "text": "Find next",
-                            "horizontal_size_policy": "Fixed",
-                            "vertical_size_policy": "Fill",
-                            "preferred_width": 150
-                        }
-                    ]
-                },
-                {
-                    "class": "GUI::Widget",
-                    "name": "replace_widget",
-                    "fill_with_background_color": true,
-                    "horizontal_size_policy": "Fill",
-                    "vertical_size_policy": "Fixed",
-                    "preferred_height": 22,
-                    "layout": {
-                        "class": "GUI::HorizontalBoxLayout"
-                    },
-                    "children": [
-                        {
-                            "class": "GUI::Button",
-                            "name": "replace_previous_button",
-                            "text": "Replace previous",
-                            "horizontal_size_policy": "Fixed",
-                            "vertical_size_policy": "Fill",
-                            "preferred_width": 100
-                        },
-                        {
-                            "class": "GUI::Button",
-                            "name": "replace_next_button",
-                            "text": "Replace next",
-                            "horizontal_size_policy": "Fixed",
-                            "vertical_size_policy": "Fill",
-                            "preferred_width": 100
-                        },
-                        {
-                            "class": "GUI::Button",
-                            "name": "replace_all_button",
-                            "text": "Replace all",
-                            "horizontal_size_policy": "Fixed",
-                            "vertical_size_policy": "Fill",
-                            "preferred_width": 100
-                        }
-                    ]
-                }
-            ]
-        },
-        {
-            "class": "GUI::StatusBar",
-            "name": "statusbar"
-        }
-    ]
-}
diff --git a/Applications/TextEditor/TextEditorWidget.cpp b/Applications/TextEditor/TextEditorWidget.cpp
index 9d8e6e9e4b..6325a1a0a0 100644
--- a/Applications/TextEditor/TextEditorWidget.cpp
+++ b/Applications/TextEditor/TextEditorWidget.cpp
@@ -30,7 +30,7 @@
 #include <AK/Optional.h>
 #include <AK/StringBuilder.h>
 #include <AK/URL.h>
-#include <Applications/TextEditor/MainWindowUI.h>
+#include <Applications/TextEditor/MainWindowGML.h>
 #include <LibCore/File.h>
 #include <LibCore/MimeData.h>
 #include <LibDesktop/Launcher.h>
@@ -61,7 +61,7 @@
 
 TextEditorWidget::TextEditorWidget()
 {
-    load_from_json(main_window_ui_json);
+    load_from_gml(main_window_gml);
 
     auto& toolbar = static_cast<GUI::ToolBar&>(*find_descendant_by_name("toolbar"));