message: `_` when used with operator should be linewise
  So `d_` is the same as `dd`, `y_` is the same as `yy`, etc.
  Fixes
diff: @@ -731,10 +731,11 @@ class MoveDownUnderscore extends BaseMovement {
  vimState: VimState,
  count: number
  ): Promise<Position | IMovement> {
  - return TextEditor.getFirstNonWhitespaceCharOnLine(
  - vimState.document,
  - position.getDown(Math.max(count - 1, 0)).line
  - );
  + vimState.currentRegisterMode = RegisterMode.LineWise;
  + const pos = position.getDown(Math.max(count - 1, 0));
  + return vimState.recordedState.operator
  + ? pos
  + : TextEditor.getFirstNonWhitespaceCharOnLine(vimState.document, pos.line);
  }
  }
  