Added environment module. Cleaned up compile warnings.
Implemented Environment mutation methods and signals
Implemented the basic environment shortcut construction
Implemented actual uniform binding using the environment shortcut
Uniform blocks and raw buffers support implemented
Added buffer usage enum. Implemented environment variables safety checks.
Refactored environment shortcut construction and verification. Implemented uniforms semantic matching.
Merge branch 'envir' of https://github.com/kvark/gfx-rs into kvark-envir

Conflicts:
	src/gfx/lib.rs
Merge branch 'kvark-envir'