The existing implementation (which triggers on }) is fairly simple and
- doesn't trigger frequently/regularly enough (particularly in editors that type the } for you)
- often reformats too much code around the edit
- has jarring cases that I don't have clear ideas for fixing
This implementation is designed to trigger on newline, which feels to me more
intuitive than } or ;.
It does have allow for reformatting after other characters - it has a
basic behavior and a model for adding specialized behavior for
particular characters. But at least initially I'd stick to advertising
\n in the capabilities.
This also handles comment splitting: when you insert a line break inside
a line comment, it will make the new line into an aligned line comment.
Working on tests, but want people to patch it in and try it - it's hard to
see if "feel" is right purely by looking at a test.