auto-texture: Adds cogl-auto-texture.h header

This moves all of the automagic texture constructor prototypes from
cogl-texture.h into a new deprecated/cogl-auto-texture.h file. This also
moves cogl_texture_new_from_sub_texture() into
deprecated/cogl-auto-texture.c

Reviewed-by: Neil Roberts <neil@linux.intel.com>
framebuffer: move fb stack under cogl/deprecated/

This moves the framebuffer stack apis out of cogl-framebuffer.c into
cogl/deprecated/cogl-framebuffer-deprecated.c so cogl-framebuffer.c is
more in-line with the master branch to ease cherry picking patches.

Reviewed-by: Neil Roberts <neil@linux.intel.com>
expose deprecated fb api regardless of COGL_ENABLE_EXPERIMENTAL_2_0_API

test-path for example uses COGL_ENABLE_EXPERIMENTAL_2_0_API to access
the 2.0 CoglPath api but also uses deprecated framebuffer api such as
cogl_push/pop_framebuffer. Similarly clutter-backend.c builds with
COGL_ENABLE_EXPERIMENTAL_2_0_API and uses cogl_set_framebuffer().

Reviewed-by: Neil Roberts <neil@linux.intel.com>