Also point to mujoco-bin for licenses

* Reraising mujoco error exceptions

Mujoco 2.0.2.3 

* Initialize perturbations properly.

* Expose "set constants" mujoco operation.

* Updated README documentation.

* Removed the 'alpha' pre-release version info.

* Fixing pip install command that seems to help with docker build in CI.

* Updating README to the next major version.

* improvements to sim.ray()

* typo

* group filter is bytes

* Add build directory to the git ignore file.

* Updating mujoco-py for mujoco 2.0

* Removing commented out test.

* Remove windows support.

* Alpha version prerelease.

* read depth buffer

* add test for read_depth_buffer

* bump version

* add raycasting utility method to mjsim

* DRY raycasting testing a bit more

* add geomgroup default arg

* remove geomgroup for now

* print helpful message instead of get compile/load error

* bump version

Fixes #294