Add ALEStartLint autocmd

This grew out of my work in #1193; to ensure the statusline was being
updated I had to add:

    fun! s:redraw(timer)
        redrawstatus
    endfun

    augroup ALEProgress
        autocmd!
        autocmd BufWritePost * call timer_start(100, function('s:redraw'))
        autocmd User ALELint redrawstatus
    augroup end

Which kind of works, but is ugly. With this, I can replace the
`BufWritePost` with:

    autocmd User ALEStartLint redrawstatus

Which is much better, IMHO.

Actually, this patch actually replaces adding a function, since you can
do:

    augroup ALEProgress
        autocmd!
        autocmd User ALEStartLint hi Statusline ctermfg=darkgrey
        autocmd User ALELint      hi Statusline ctermfg=NONE
    augroup end

or:

    let s:ale_running = 0
    let l:stl .= '%{s:ale_running ? "[linting]" : ""}'
    augroup ALEProgress
        autocmd!
        autocmd User ALEStartLint let s:ale_running = 1 | redrawstatus
        autocmd User ALELint      let s:ale_running = 0 | redrawstatus
    augroup end

Both seem to work very well in my testing.

No need to `ale#Statusline#IsRunning()` anymore, I think?

1 files changed, 24 insertions, 1 deletions

diff --git a/test/test_alelint_autocmd.vader b/test/test_alelint_autocmd.vader
index 4503005b..bf96abfb 100644
--- a/test/test_alelint_autocmd.vader
+++ b/test/test_alelint_autocmd.vader
@@ -1,18 +1,41 @@
 Before:
+  let g:start = 0
   let g:success = 0
   let g:ale_run_synchronously = 1
 
+  function! TestCallback(buffer, output)
+    return [{
+    \ 'lnum': 1,
+    \ 'col': 3,
+    \ 'text': 'baz boz',
+    \}]
+  endfunction
+
+  call ale#linter#Define('foobar', {
+  \ 'name': 'testlinter',
+  \ 'callback': 'TestCallback',
+  \ 'executable': has('win32') ? 'cmd' : 'true',
+  \ 'command': has('win32') ? 'echo' : 'true',
+  \})
+  "let g:ale_linters = {'foobar': ['lint_file_linter']}
+
 After:
   let g:ale_run_synchronously = 0
   let g:ale_buffer_info = {}
+  let g:ale_linters = {}
+  call ale#linter#Reset()
+  delfunction TestCallback
   augroup! VaderTest
 
 Execute (Run a lint cycle, and check that a variable is set in the autocmd):
+  set filetype=foobar
   augroup VaderTest
     autocmd!
-    autocmd User ALELint let g:success = 1
+    autocmd User ALEStartLint let g:start = 1
+    autocmd User ALELint      let g:success = 1
   augroup end
 
   call ale#Lint()
 
+  AssertEqual g:start, 1
   AssertEqual g:success, 1