A more efficient way of updating tags + Scan current file only

[MisterPresident]

This pull request is just a more efficient way of updating tags (using updateNoteTags vs. removeTags + addTags). This speeds up the generation task, especially if you have a big vault (2k notes) and a lot of tags in Anki (64k cards with ~16k tags). Alltogehter It should prevent Anki from dying due to a big request-payload.

Moreover, I added a command to scan the current file only.

This should fix #565. Maybe helps on #428, #354, #326.