gst/gstelement.c: don't loop forever

gst/gstelement.c: don't loop forever

Original commit message from CVS:
* gst/gstelement.c: (gst_element_dispose):
don't loop forever
* gst/gstiterator.c:
* gst/gststructure.c:
doc fixes
* libs/gst/controller/gstcontroller.c:
(gst_controlled_property_set_interpolation_mode):
* libs/gst/controller/gstcontroller.h:
* libs/gst/controller/gstinterpolation.c:
(interpolate_none_get_enum_value_array):
support controlling enums