Internal version number

In the next release (0.3.13), I'm going to change the format of the internal version number integer from 313 to 31300, for instance 31305 = 0.3.13.5.  The last number represents changes on the SVN between releases and ought to be properly represented in the version number.  Otherwise, it would be a pain if we had a mistake or something in one of the sub versions that needed to be worked around.