Avoid reprocessing modeline

#188
> If you set updatetime to a large enough number that you have time to open the fold, go somewhere inside of it and hit `A` or `I`, insert mode is entered and the fold is closed, which is very disorienting.

こっち (`CursorMovedI`で発動) は直っていません。
一旦 `nomodeline` に設定することで対処しました。