Added missing file ResourceLoader.inl and added functionality for "null"-handles.
Added missing class TextureLoader.
... forgot to save before commiting ResourceLoader.hpp.
Added textures to mesh and changed name of TextureLoader to TextureManger.
Updated test_gr_model.
Removed old test files.
Added missing include dir to gr_scene test.
Updated filesystem test premake file and fixed error in test module.
Updated tests so you can have error messages.
Updated filesystem classes.

- Implemented FileOutputStream.
- Updated tests.