Adds missing notices, and ensures all the notices are consistent. The Cogl
blurb also now reads:
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
Redundant clearing of depth and stencil buffers every render can be very
expensive, so cogl now gives control over which auxiliary buffers are
cleared.
Note: For now clutter continues to clear the color, depth and stencil buffer
each paint.
In unifying the {gl,gles}/cogl.c code recently, moving most of the code into
common/cogl.c the gmodule.h include was also mistakenly moved.
Thanks to Felix Rabe for reporting this issue.
Note: I haven't tested this fix myself, as I'm not set up to be able to
build for OS X
