- Back to 1-based layer names to make it clearer in editor UI
- Layer bit accessors are renamed to layer value and 1-based too
- Uniform errors and documentation in render and physics
- Fix a few remaining collision_layer used in place of collision_mask
For the time being we don't support writing a description for those, preferring
having all details in the method's description.
Using self-closing tags saves half the lines, and prevents contributors from
thinking that they should write the argument or return documentation there.
- Fixes Godot physics failing when the cast Shape is inside of, or
already colliding with another Shape.
- Fixes Bullet physics failing when there is no motion.
- Ensures Godot and Bullet physics behave the same.
- Updates the documentation to exclude the caveats for the failures and
differences.
