atlas-texture: use COGL_TEXTURE_DEFINE macro

It was an oversight when making the CoglAtlasTexture api public that we
continued to use the COGL_TEXTURE_INTERNAL_DEFINE macro. This updates
the code to now use COGL_TEXTURE_DEFINE which means the
cogl_is_atlas_texture() function will now be exported in the public api.

Reviewed-by: Neil Roberts <neil@linux.intel.com>
Reviewed-by: Lionel Landwerlin <llandwerlin@gmail.com>

(cherry picked from commit ecbe209f48be80fe45b48f92b277a2aee08d5704)
tests: use 'FIXME' instead of 'fail' for expected failures

Seeing 'fail' in the test reports and the explanation that it means
"Test failed, but it was an expected failure" somewhat gives the
impression that these failures are ok. Actually these failures represent
known bugs/issues that we haven't yet fixed but we don't want them to
result in 'make check' ailing. To try and better reflect the severity of
these issues we now report them as 'FIXME'.

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

(cherry picked from commit 7934bf3ee4356af160b63084c7192fd2965b5ddd)
cogl1: fix comments from cogl_clip_push_rectangle

Reviewed-by: Robert Bragg <robert@linux.intel.com>
cogl: add missing colon in headers

Reviewed-by: Robert Bragg <robert@linux.intel.com>
quaternion: fix structure introspection annotation

Reviewed-by: Robert Bragg <robert@linux.intel.com>
pipeline: fix method description

Reviewed-by: Robert Bragg <robert@linux.intel.com>
texture-2d-sliced: fix argument description

Reviewed-by: Robert Bragg <robert@linux.intel.com>
texture-2d-gl: fix argument description

Reviewed-by: Robert Bragg <robert@linux.intel.com>
texture-rectangle: fix argument description

Reviewed-by: Robert Bragg <robert@linux.intel.com>
onscreen-template: fix argument description

Reviewed-by: Robert Bragg <robert@linux.intel.com>
atlas-texture: fix argument description

Reviewed-by: Robert Bragg <robert@linux.intel.com>
attribute: fix argument description

Reviewed-by: Robert Bragg <robert@linux.intel.com>
glib-source: fix argument description

Reviewed-by: Robert Bragg <robert@linux.intel.com>