LibVT+Kernel: Clean up scroll API

This commit cleans up some of the `#ifdef`-ed code smell in
`Terminal`, by extending the scroll APIs to take a range of lines as a
parameter. This makes it possible to use the same code for `IL`/`DL` as
for scrolling.

Note that the current scrolling implementation is very naive, and does
many insertions/deletions in the middle of arrays, whereas swaps should
be enough. This optimization will come in a later commit.

The `linefeed` override was removed from `VirtualConsole`. Previously,
it exhibited incorrect behavior by moving to column 0. Now that we use
the method defined in `Terminal`, code which relied on this behavior
stopped working. We go instead go through the TTY layer which handles
the various output flags. Passing the input character-by-character
seems a bit excessive, so a fix for it will come in another PR.

1 files changed, 3 insertions, 2 deletions

diff --git a/Kernel/TTY/TTY.h b/Kernel/TTY/TTY.h
index 9e5ee61bfd..7813b0abf9 100644
--- a/Kernel/TTY/TTY.h
+++ b/Kernel/TTY/TTY.h
@@ -58,7 +58,7 @@ protected:
 
     TTY(unsigned major, unsigned minor);
     void emit(u8, bool do_evaluate_block_conditions = false);
-    virtual void echo(u8) = 0;
+    void echo_with_processing(u8);
 
     bool can_do_backspace() const;
     void do_backspace();
@@ -80,7 +80,8 @@ protected:
 private:
     // ^CharacterDevice
     virtual bool is_tty() const final override { return true; }
-    inline void echo_with_processing(u8);
+
+    virtual void echo(u8) = 0;
 
     template<typename Functor>
     void process_output(u8, Functor put_char);