Background fix
Merge branch 'dev' of https://github.com/aerys/minko into dev

Conflicts:
	src/aerys/minko/render/shader/background/BackgroundLayerShader.as
Change multi pass priority offset to avoid collision with alpha reduction priority in passes
Fix zNear parameter that triggered multiple errors on shader post optimization
Fix alpha threshold on multi pass phong effect
Update Matrix4x4.as

fix bug at appendTranslation & prependTranslation
Merge pull request #146 from MerlinTwi/patch-4

Fix a bug where matrix components were not correctly invalidated.
Added optional textureResource parameter to TextureLoader, in order to load a texture to an existing TextureResource
Fix specular when normal map is set manually inside the shader
Added automatic texture reloading with TextureLoader.loadClass and TextureLoader.load on context loss
Moved some code so that context loss is also handled when using a textureLoader object
Change multi pass priority offset to avoid collision with alpha reduction priority in passes
Fix zNear parameter that triggered multiple errors on shader post optimization
Fix alpha threshold on multi pass phong effect
Added optional textureResource parameter to TextureLoader, in order to load a texture to an existing TextureResource
Fix specular when normal map is set manually inside the shader
Added automatic texture reloading with TextureLoader.loadClass and TextureLoader.load on context loss
Moved some code so that context loss is also handled when using a textureLoader object
Merge remote-tracking branch 'refs/remotes/origin/dev' into dev
Remove warning.