Implements a basic way to 'group' affixes together.

An affix group is a collection of affixes which generally provide the
same benefits, but at varying levels. For example, '+2 strength' and '+4
strength' would be considered grouped affixes, assuming that they were
spawning on the same items and such

This pulls out the reading of effect details from our data files to a
new class that is referenced by Effect, EffectRepo

Add some javadoc comments

Cleanup some warnings

There was something in ReplPair that was causing issues. Since we don't
need any of the fancy ReplPair functionality, I ripped it all out, since
it was causing issues (probably sorting-related, with a comparator or
something missing somewhere)

AffixLister got refactored some more, in preparation for adding the
ability to load things that aren't affixes.

This splits AffixLister into a separate file for each class that it once
contained.