Better mass, higher FPS

Some quick small updates (v0.3.11) thanks to feedback from SimonR404:

• FPS was previously locked at 30, now set to 60.
• Fragments were supposed to have mass relative to their size, but didn't. Now they do.

Tomorrow I hope to look at outlining fragments instead of highlighting (to help with matching colors), and possibly an alternate rotation scheme that has less chance of going wild on you. Thanks!