Revision 3892

I've modified the renameCourse code to simply issue a warning when a
course directory (other than the course root dir) is not movable. I've
also added error checking for some of the more common reasons for
directories to not be movable, so that the warning message is more
informative.

Resolves bug #943.
Originally committed to branch rel-2-2-dev.
Forward-ported without modification to HEAD.