Add Event.maxPoints and getter

A brief glance at version 1 of this app reminded me that a max-points
mechanism is necessary. I have thus added it.

This will be used when computing points for a school. (I'll probably add
a new method to EventResults that calls computeTotalSweeps but enforces
this cap.) I'll be adding to the Event constructor as well; that's
probably going to be the next commit.
Add maxPoints to Event constructor and configuration syntax

The "oo" syntax for an infinite value is based on the map XML files for
the Minecraft server oc.tc, where "oo" represents an infinite coordinate
when specifying regions. The other syntaxes are intended for human
readability.