* tests/test-events.c: Clean up a bit, and print out more
messages when pressing one of the rectangles.
* tests/test-threads.c: Be more verbose in the console, and
apply another behaviour on the rectangle, to show that we
are not blocking.
* clutter.symbols:
Added a bunch of missing symbols.
* clutter/clutter-script.c:
* json/json-node.c:
Use g_slice_new0 instead of g_slice_new to avoid passing garbage to functions.
* tests/test-threads.c:
Replaced non-portable sleep() with g_usleep().
