added framebuffer to canvas
Merge remote-tracking branch 'upstream/develop' into fbo

Conflicts:
	engine/src/main/java/org/terasology/engine/subsystem/lwjgl/LwjglGraphics.java
FBO uses normal texture
fixed on viewport when drawing to texture
bugfix
Flipped the fbo texture
Merge branch 'develop' into nui-fbo

Conflicts:
	engine/src/main/java/org/terasology/rendering/nui/layouts/miglayout/MigLayout.java
Refactored FrameBufferObject so that the Lwjgl-specific implementation is separated from a generic interface that is used by CanvasRenderer.
Merge pull request #1053 from immortius/nui-fbo

NUI FrameBufferObject support