COGL has a debug message system like Clutter's own. In parallel,
it also uses a coupld of #defines. Spread around there are also
calls to printf() instead to the more correct g_log* wrappers.
This commit tries to unify and clean up the macros and the
debug message handling inside COGL to be more consistent.
The code for the conversion of the GL error enumeration code
into a string is not following the code style and conventions
we follow in Clutter and COGL.
The GE() macro is also using fprintf(stderr) directly instead
of using g_warning() -- which is redirectable to an alternative
logging system using the g_log* API.
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