ext/soundtouch/gstpitch.cc: Allow seeking only in TIME and DEFAULT format, other...

ext/soundtouch/gstpitch.cc: Allow seeking only in TIME and DEFAULT format, other formats will not work as expected. A...

Original commit message from CVS:
* ext/soundtouch/gstpitch.cc:
Allow seeking only in TIME and DEFAULT format, other formats will
not work as expected. Also handle a stop position of -1 correctly
for seeks, newsegment events and the queries. This fixes playback
with the pitch element if upstream doesn't know the duration or has
-1 as stop position in NEWSEGMENT events for other reasons. Before
simply nothing was played as the segment was going from 0 to 0.
Send a GST_MESSAGE_DURATION whenever the rate or tempo is changed
so applications can update their cached duration. Fixes bug #503308.
Some random cleanup and memory leak closing.