gst/videocrop/gstvideocrop.*: Fix renegotiation when changing properties using the new basetransform features. Fixes ...

Original commit message from CVS:
* gst/videocrop/gstvideocrop.c: (gst_video_crop_init),
(gst_video_crop_transform), (gst_video_crop_transform_caps),
(gst_video_crop_set_caps), (gst_video_crop_set_property):
* gst/videocrop/gstvideocrop.h:
Fix renegotiation when changing properties using the new basetransform
features. Fixes #561502.
* tests/icles/Makefile.am:
* tests/icles/videocrop2-test.c: (make_pipeline), (main):
Add crazy interactive test unit for dynamically changing properties.