Vector print wrapper

See results here:

http://nbviewer.ipython.org/gist/moorepants/8889548

Also, I'm closing PR #2833 to default to this version.

Tasks:

- [x] Make init_printing be init_vprinting?
- [x] Make the printing functions available in vector/functions.
- [x] Add deprecation warnings to the mechanics functions (or just leave support?).
- [x] mechanics_printing is a little different now if you want mechanics string printing. you have to use the `pretty_print=False` flag. This is an api change of sorts. I can't imagine it breaking anything major, but maybe. Should we retain a mechanics printing function that only does string printing like before? Or make deprecations for it?