Fixed constantly mipmap generation

Fixed bug when setting MinFilter with mipmapping after generating mipmaps causes jME to update image data every frame.
Merge pull request #129 from Rena4ka/master

Fixed constantly mipmap generation
The ShaderNodes system now correctly handles swizzle of types like ivecn, uvecn, bvecn
The shaderNodesGenerator now properly declare and assign inPosition :
inPosition can be a vec4 or Vec3 and will be assign to Global.position accordingly
Fixed typo in previous commit's javadoc
Update CONTRIBUTING.md

Added link to the awesome cheat sheet:
https://github.com/tiimgreen/github-cheat-sheet/blob/master/README.md
Added README.md v1

Shorter summary. Pretty games mashup and popular games list. Basic getting started section along with essential links.
Made a MaterialDebugAppState that allows hot reload of materials at runtime. Pretty convenient for shader development and debugging