v0.3.0-beta1

First beta release. API should remain fairly stable until the second beta or rc1, whichever comes first.

Changes since last alpha:

• Cleaned up, updated, and improved documentation.
• Added parameter to Isaac Gym runner to set max_gpu_contact_pairs, which controls memory allocated for storing contacts during simulation. Users need to tune the value of this parameter to their specific use case.
• Fixed names and implementations of EA population and selection functions.