Mega update of INFO, DEBUG, and ERROR subsystems, renamed with GST_ prefix.

Mega update of INFO, DEBUG, and ERROR subsystems, renamed with GST_ prefix.

Original commit message from CVS:
Mega update of INFO, DEBUG, and ERROR subsystems, renamed with GST_ prefix.
GST_DEBUG now takes a category parameter, which is the same as GST_INFO
system.  They are now called GST_CAT_*.  All the GST_DEBUGs are set to 0
for now, we need to go and fix all these eventually.