Move powerline to utilities

The new version of powerline requires a slightly more involved setup, so
getting it out of the general category is probably for the best.
Add repeat, abolish, and characterize

Repeat will make a few existing plugins repeatable with ., abolish is
currently in testing to see if it's useful to me, and characterize seems
like a decent candidate for a permanent spot in utilities, perhaps to be
moved to the HTML section.