As part of an on-going effort to get cogl-pipeline.c into a more
maintainable state this splits out all the apis relating just to
layer state. This just leaves code relating to the core CoglPipeline
and CoglPipelineLayer design left in cogl-pipeline.c.
This splits out around 2k more lines from cogl-pipeline.c although we
are still left with nearly 4k lines so we still have some way to go!
Reviewed-by: Neil Roberts <neil@linux.intel.com>
