message: Support <C-u> in command line / search bar
  Refs
diff: @@ -895,6 +895,7 @@ class CommandInsertInSearchMode extends BaseCommand {
  ['<C-p>'], // Previous
  ['<C-n>'], // Next
  ['<C-f>'], // Find
  + ['<C-u>'], // Delete to beginning
  ['<Home>'],
  ['<End>'],
  ['<Del>'],
  @@ -928,6 +929,11 @@ class CommandInsertInSearchMode extends BaseCommand {
  position,
  vimState
  );
  + } else if (key === '<C-u>') {
  + searchState.searchString = searchState.searchString.slice(
  + vimState.statusBarCursorCharacterPos
  + );
  + vimState.statusBarCursorCharacterPos = 0;
  } else if (key === '<Del>') {
  searchState.searchString =
  searchState.searchString.slice(0, vimState.statusBarCursorCharacterPos) +
  @@ -2022,6 +2028,7 @@ class CommandInsertInCommandline extends BaseCommand {
  ['<C-p>'], // Previous
  ['<C-n>'], // Next
  ['<C-f>'], // Find
  + ['<C-u>'], // Delete to beginning
  ['<Home>'],
  ['<End>'],
  ['<Del>'],
  @@ -2046,6 +2053,11 @@ class CommandInsertInCommandline extends BaseCommand {
  vimState.statusBarCursorCharacterPos = Math.max(vimState.statusBarCursorCharacterPos - 1, 0);
  } else if (key === '<C-f>') {
  new CommandShowCommandHistory().exec(position, vimState);
  + } else if (key === '<C-u>') {
  + vimState.currentCommandlineText = vimState.currentCommandlineText.slice(
  + vimState.statusBarCursorCharacterPos
  + );
  + vimState.statusBarCursorCharacterPos = 0;
  } else if (key === '<Del>') {
  vimState.currentCommandlineText =
  vimState.currentCommandlineText.slice(0, vimState.statusBarCursorCharacterPos) +
  