Merge pull request #343 from csherratt/master

rename gl to gfx_gl
Fix gl-init crate name
Move contents of renderer::front into root module

This makes the module structure more consistent with the device module.
Add screenshots of examples to their README
Rename State to RenderState for clarity
Move Graphics type to gfx crate

Because the type ties together both the renderer and device, it makes more sense for it to be in the common crate.
Merge pull request #344 from lucidd/339

Add example screenshots and fix gl-init crate name
Formatting cleanups
Merge pull request #345 from bjz/render-restructure

Render crate reorganisations
Depend on external gfx_gl repository
Merge pull request #347 from bjz/gfx_gl

Depend on external gfx_gl repository
Implemented Ord for RefBatch
Merge pull request #348 from sectopod/ord

Implemented Ord for RefBatch
Added CommandBuffer export
Merge pull request #349 from sectopod/ord

Added CommandBuffer export
Add dependency diagram to README
Simplify diagram by leaving out the other dependencies for the examples
Use .dot file extension
Merge pull request #350 from bjz/diagram

Add dependency diagram to README
Add windowing libraries to dependency graph

Helps to demonstrate that gfx-rs is decoupled from a single windowing library.