Crafty 0.9.0-rc2

Second release candidate for version 0.9.0, fixing a couple of bugs with rc1.

Changes from 0.8.0:

• Numerous optimizations, at the cost of a larger than normal number of breaking changes (see release notes for a full list)
• Improvements to the control systems
• Shorthand for defining getter/setters as part of components
• Allow freezing/unfreezing entities (temporarily remove them from rendering/collision/motion systems.)

Here's the full release notes, and preview documentation is available. (Though you can also see the docs locally with grunt view-api.)