A temporal expression library I was working on for my Symfony2 CalendarBundle. I decided to take a
completely different direction, and so the Expression component was no longer needed. I couldn't
bring myself to throw the code into the trash bin, though.

I'll likely update this to actually function as an independent library somewhere down the line.

Code is based off of a port of a C# temporal expression library called garbagetruck.
http://code.google.com/p/garbagetruck/