Fix a memleak in gst_cmml_track_list_add_clip.

Fix a memleak in gst_cmml_track_list_add_clip.

Original commit message from CVS:
2006-02-25  Alessandro Decina <alessandro@nnva.org>

* ext/annodex/Makefile.am:
* ext/annodex/gstannodex.c:
* ext/annodex/gstcmmldec.c:
* ext/annodex/gstcmmlenc.c:
* ext/annodex/gstcmmlparser.c:
* ext/annodex/gstcmmlparser.h:
* ext/annodex/gstcmmlutils.c:
* tests/check/elements/cmmldec.c:
* tests/check/elements/cmmlenc.c:
Fix a memleak in gst_cmml_track_list_add_clip.
Handle overflows in clip's start and end times.
Add the "encoded" parameter to cmmldec and cmmlenc caps.
Do not parse junk at the end of a CMML preamble buffer.
Register a libxml error handler to not print stuff on stderr.
Check for bad clip start and end times in the testsuites.