GCC has some optimization for the inclusion guard, but they only work if
the check is the outermost one.
We're fairly inconsistent because of historical reasons, so we should
ensure that we follow the same pattern in every public header.
Since EGA colors are apparently all the rage in other toolkits, Clutter
should not be left out. On top of the usual CGA/EGA palette the static
colors also include the Tango Icon palette, which at least is more
pleasant to the eye.
Static colors are accessed through an enumeration by using
clutter_color_get_static(), or using the short-hand pre-processor
macros.
http://bugzilla.clutter-project.org/show_bug.cgi?id=2066
