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
typos in Spatial.java comments as discussed at http://hub.jmonkeyengine.org/forum/topic/typos-in-spatial-java-comments/
remove CRs from line endings (added in previous commit)
corrections to com.jme3.scene.* comments as discussed at http://hub.jmonkeyengine.org/forum/topic/typos-in-com-jme3-scene/
Feature: added support for bone envelopes.
Merge pull request #132 from phr00t/master

- performance improvements to PhysicsSpace - thanks to @phr00t
- ups jME Java dependence to Java 1.6
- change push() --> add() for physics collision events
correct core comments and standardize line endings as discussed at http://hub.jmonkeyengine.org/forum/topic/typos-in-com-jme3-mathrendererpost/
Merge branch 'master' of https://github.com/jMonkeyEngine/jmonkeyengine.git
- Fixed the GammaCorrectionFilter so it properly works with multisampling, will be used as a fall back to upcoming Gamma Correction implementation
- Removed luma
- Passed inverse gamma instead of gamma to avoid doing a division for each pixel in the shader
- Added an AppSetting param for gamma correction, defaulted to true.
- Added a filed in the Setting dialog to toggle gamma correction on and off
Added support for hardware srgb output (gamma correction).
It can be toggled at render time.
Works with lwjgl
Couldn't test with Jogl and might be not working
Not supported by mobile renderers
- Image loaders now assume ALL images are in sRGB space and set the flag accordingly
- All images constructors now take the isSrgb flag as a parameter, all engine classes has been changed to accommodate the change, old constructors has been deprecated for backward compatibility. One should always ask himself in which color space is an image if dealing with gamma correction
- Gamma correction has been defaulted to false in the appSettings