Incomplete refactoring of Event code
I kill the crappy enum conversion functions and they just come back
stronger and meaner than before. This time Jackson has started giving
a strange error when trying to map my enums properly, and I don't
understand why, so I've reinstated the string converters for now.
More refactoring, renaming, and simplification of the Event handing
code. It's still not done yet, but things are slowly getting near
to the point where everything will work...