check/gst-libs/controller.c: more tests (hehe I have the most)

check/gst-libs/controller.c: more tests (hehe I have the most)

Original commit message from CVS:
* check/gst-libs/controller.c: (gst_test_mono_source_get_property),
(gst_test_mono_source_set_property),
(gst_test_mono_source_class_init), (GST_START_TEST),
(gst_controller_suite):
more tests (hehe I have the most)
* gst/gstbus.c:
describe popping messages whenusing mulltiple sources
* libs/gst/controller/gst-controller.c:
(gst_controlled_property_set_interpolation_mode),
(gst_controlled_property_new):
* libs/gst/controller/gst-controller.h:
* libs/gst/controller/gst-interpolation.c:
implement boolean properties