gst/: widen the debug category in output to fit the biggest one we have add a bus category and use it play with the c...

Original commit message from CVS:

* gst/gst_private.h:
* gst/gstbus.c:
* gst/gstelement.c:
* gst/gstinfo.c:
* gst/gstpluginfeature.c:
widen the debug category in output to fit the biggest one we have
add a bus category and use it
play with the colors
fix up some categories