Pre-Release of Asteroid Type System

This is an early release of Custom Asteroids 1.3, which will be released soon after KSP 1.1. Custom Asteroids 1.3 will add many new features to asteroid configurations as well as changing the format of the download bundle, so I'd like user feedback before the release.

Key changes:

• Asteroid config files, parts, and science definitions separated from the "main" Custom Asteroids install. [Note: the version for 1.1.0.1209 separates only the asteroid config files, to make things simpler for 3rd-party modders.]
• Partial support for custom asteroid types.
• Can now customize asteroids on intercept trajectories.
• Asteroids can now appear only under certain conditions.
• Asteroid orbits can now be given relative to an inclined plane. Useful for mods like RSS and Harder Solar System.