Run reviewer.Reviewer.correct as a filter. Should help add-on authors.

This is basically a repeat of #22, updated for version 2.0.10

Run `correct()` as a filter so add-ons can cleanly modify the red/green corrected version of a typed answer.

I have already written two add-ons that both monkey-patch the `typeAnsAnswerFilter()` function where the `correct()` is called. Like this these add-ons would be much cleaner. It might also be of help with [issue 1445](https://anki.tenderapp.com/discussions/ankidesktop/1445).

The card is passed along so the add-ons can get an idea what is going on. (My add-ons only do their own correcting when the field had the right name.)