Automatic registration of engine types

[randomPoison]

The engine provides a lot of component and resource types and it quickly becomes a pain to manually remember every one that you need to register when using the editor with your game. It would be better if this crate provided a way to automatically register all the engine-provided types.

For convenience this functionality should be enabled by default, but there should be a way to disable it in case there is any use case where the user wouldn't want to register all the engine types.

Here's a list of types we should start with:

• AmbientColor
• Light
• Named
• Shape
• RotationControl
• Camera
• Transform
• GlobalTransform

[AnneKitsune]

Imo, I think it shouldn't be doing that by default. Maybe a .with_default_types() function?

Also, amethyst will eventually have feature gates to reduce compilation times. Things like the renderer or the physics will be activable/deactivable by the end user. You should plan forward to that if possible.

[randomPoison]

This was closed by #21.