Revision 7104

removed hardwiring of the user, session_key and courseID from all of the xmlrpc functions.

an xmlrpc call must be to an existing course and the user must be in the course,
must have a current session_key and must have instructor privileges.

no provision yet for obtaining a session_key if a session times out.

added a good many error checks.  Most of them turned off
but there is a trace of xmlrpc calls that is placed in the apache log