Version 2.3 released

As it is going to be a bit before I get the 3.0 release out, I decided to issue a 2.3 release with a few minor changes. The next release should be 3.0 with a new file format.... unless, of course, I decide to go off and build a Tkinter interface for it.

Note that I did create a branch in CVS (BRANCH_R_2_3) so that the 3.0 code is still in HEAD.