Re-order the units into a sensible list, with basic tests at the
beginning, and per-class tests at the end - with Cogl last.
Also, start renaming the unit functions from test_<foo> to <foo>,
so that the executable wrappers and the reports have sensible names.
This unit verifies that an Actor class will invoke the get_preferred_*
virtual functions unless the caching is in effect; it also verifies
that the cached values are correctly evicted.
The size requisition and allocation mechanisms should be thoroughly
tested to avoid unwanted regressions.
For starters, we can test the explicit size setting and the side
effects of calling clutter_actor_set_size().
