Fix #1619 - Rewrite lint on enter events so they behave better

test/test_no_linting_on_write_quit.vader

@@ -3,9 +3,21 @@ Before:
   Save g:ale_fix_on_save
   Save g:ale_fixers
   Save g:ale_lint_on_save
+  Save g:ale_set_highlights
+  Save g:ale_set_lists_synchronously
+  Save g:ale_set_loclist
+  Save g:ale_set_quickfix
+  Save g:ale_set_signs
 
-  let g:ale_echo_cursor = 0
   let g:ale_run_synchronously = 1
+  let g:ale_set_lists_synchronously = 1
+  " Disable the things we don't need, but leave enabled what we do.
+  let g:ale_echo_cursor = 0
+  let g:ale_set_signs = 0
+  let g:ale_set_quickfix = 0
+  let g:ale_set_loclist = 1
+  let g:ale_set_highlights = 0
+  let g:ale_echo_cursor = 0
 
   function! TestCallback(buffer, output)
     return [{'lnum': 1, 'col': 1, 'text': 'xxx'}]
@@ -19,6 +31,7 @@ Before:
   \ 'testft': ['AddLine'],
   \}
 
+  call ale#linter#PreventLoading('testft')
   call ale#linter#Define('testft', {
   \ 'name': 'testlinter',
   \ 'callback': 'TestCallback',