renamed gsttag -> gsttaglist, gsttaginterface -> gsttagsetter inlined docs for gsttrace, gsttrashstack

Original commit message from CVS:
* docs/gst/gstreamer-docs.sgml:
* docs/gst/tmpl/.cvsignore:
* docs/gst/tmpl/gsttrace.sgml:
* docs/gst/tmpl/gsttrashstack.sgml:
* gst/Makefile.am:
* gst/gst.h:
* gst/gstelement.h:
* gst/gstevent.h:
* gst/gstmessage.c:
* gst/gstmessage.h:
* gst/gsttag.c:
* gst/gsttag.h:
* gst/gsttaginterface.c:
* gst/gsttaginterface.h:
* gst/gsttaglist.c:
* gst/gsttaglist.h:
* gst/gsttagsetter.c:
* gst/gsttagsetter.h:
* gst/gsttrace.c:
* gst/gsttrace.h:
* gst/gsttrashstack.c:
renamed gsttag -> gsttaglist, gsttaginterface -> gsttagsetter
inlined docs for gsttrace, gsttrashstack