Fix grammar in comments.
Fix some indent problems.
Do not corrupt textures between FBOs

Previously, if we set a texture (e.g. tex0) and some parts of it
were transparent, all the transparent things would have been changed
when doing fxobject[0].draw(...). The transparent parts would have
had their alpha channel mixed with the black color due to the
ofClear(0,0) call in setTexture. Now we no longer destroy textures.
OpenGL3 support for ofxBloom.h