testsuite/interface.py (Availability.testXOverlay): Extend to test method calling...

testsuite/interface.py (Availability.testXOverlay): Extend to test method calling on interfaces

Original commit message from CVS:
* testsuite/interface.py (Availability.testXOverlay): Extend to
test method calling on interfaces

* testsuite/common.py: call pygtk.require first

* gst/gstbin.override (_wrap_gst_bin_get_by_name): Add a
keyword argument recurse and remove
_wrap_gst_bin_get_by_name_recurse_up.

* gst/gst.override (_wrap_gst_element_get_pad_list): Split out bin
functions to ...

* gst/gstbin.override: .. this file

* gst/gst.defs (bin_new): allow NULL for first argument.
(child_state_change): Remove, it's private.