gst/videodrop/gstvideodrop.*: Work based on timestamp of input data, not based on...

gst/videodrop/gstvideodrop.*: Work based on timestamp of input data, not based on the expected framerate from the inp...

Original commit message from CVS:
* gst/videodrop/gstvideodrop.c: (gst_videodrop_init),
(gst_videodrop_chain), (gst_videodrop_change_state):
* gst/videodrop/gstvideodrop.h:
Work based on timestamp of input data, not based on the expected
framerate from the input. The consequence is that this element now
not only scales framerates, but also functions as a framerate
corrector or framerate stabilizer/constantizer.