Original commit message from CVS:
* gst/debug/testplugin.c:
* gst/debug/tests.c:
* gst/debug/tests.h:
add new extensible and configurable testing element. Current tests
include buffer count, stream length, timestamp/duration matching and
md5.
* gst/debug/Makefile.am:
* gst/debug/gstdebug.c: (plugin_init):
add infrastructure for new element
