message: Basic support for Ctrl+R on command line
  Allows pasting from a register like in insert mode
  Fixes
diff: @@ -354,6 +354,41 @@ export class CommandRegister extends BaseCommand {
  }
  }
  +@RegisterAction
  +class CommandInsertRegisterContentInCommandLine extends BaseCommand {
  + modes = [ModeName.CommandlineInProgress];
  + keys = ['<C-r>', '<character>'];
  + isCompleteAction = false;
  +
  + public async exec(position: Position, vimState: VimState): Promise<VimState> {
  + vimState.recordedState.registerName = this.keysPressed[1];
  + const register = await Register.get(vimState);
  + let text: string;
  +
  + if (register.text instanceof Array) {
  + text = (register.text as string[]).join('\n');
  + } else if (register.text instanceof RecordedState) {
  + let keyStrokes: string[] = [];
  +
  + for (let action of register.text.actionsRun) {
  + keyStrokes = keyStrokes.concat(action.keysPressed);
  + }
  +
  + text = keyStrokes.join('\n');
  + } else {
  + text = register.text;
  + }
  +
  + if (register.registerMode === RegisterMode.LineWise) {
  + text += '\n';
  + }
  +
  + vimState.currentCommandlineText += text;
  + vimState.statusBarCursorCharacterPos += text.length;
  + return vimState;
  + }
  +}
  +
  @RegisterAction
  class CommandInsertRegisterContentInSearchMode extends BaseCommand {
  modes = [ModeName.SearchInProgressMode];
  