Issues 43 and 45 - sort(reverse=True) and a basic regular expression implementation

You can see details in the issues and commit messages:

https://github.com/bnmnetp/skulpt/issues/43
https://github.com/bnmnetp/skulpt/issues/45

I am slowing down as I have now made it all the way through the sample code for the class I am teaching currently :)

I will take a break for a while unless my students run across a glitch as they go through the autograder in the next few weeks.   After that I might go after sorted() as I use that in my teaching but not in my assignments for the current class.