Add rad module

RAD stands for Rapid Application Development

 - add a way to retrieve the list of components of an entity
 - add a way to retrieve a specific user game state, for serialisation

Serialisation seems to work, deserialisation is not ready yet
Add a makedirs function

Same as os.makedirs except it only work in the write dir!
Color might string or int
Add a Rapid Application Development module

And change a few thing in the current api:

  - systems are now unloaded when state is unloaded
  - no more configure methods
Internal refactoring + cleanup log messages