The cogl_is_* functions were showing up quite high on profiles due to
iterating through arrays of cogl handles.
This does away with all the handle arrays and implements a simple struct
inheritance scheme. All cogl objects now add a CoglHandleObject _parent;
member to their main structures. The base object includes 2 members a.t.m; a
ref_count, and a klass pointer. The klass in turn gives you a type and
virtual function for freeing objects of that type.
Each handle type has a _cogl_##handle_type##_get_type () function
automatically defined which returns a GQuark of the handle type, so now
implementing the cogl_is_* funcs is just a case of comparing with
obj->klass->type.
Another outcome of the re-work is that cogl_handle_{ref,unref} are also much
more efficient, and no longer need extending for each handle type added to
cogl. The cogl_##handle_type##_{ref,unref} functions are now deprecated and
are no longer used internally to Clutter or Cogl. Potentially we can remove
them completely before 1.0.
* clutter/cogl/gles/cogl-fbo.c: Copy the code from gl/cogl-fbo but
use the API calls directly instead of loading an extension because
it is part of the core in GLES 2.
* clutter/cogl/gles/cogl.c (_cogl_features_init): Report
COGL_FEATURE_OFFSCREEN.
* clutter/cogl/gles/cogl-fbo.h (CoglFbo): Add gl_stencil_handle.
* clutter/cogl/gles/cogl-context.h (CoglContext): Add
viewport_store
* tests/test-fbo.c (make_shader): Conditionally use the GLES 2
names of the shader variables
