Add a skeletal computeTotalSweepsCapped

Note that this still requires a proper comparison function for Fraction,
which I will now implement.
Make Fraction implement Comparable
Finish EventResults.computeTotalSweepsCapped

I was missing comparison logic, which required me to implement
Comparable.
Add FractionTest.testCompareTo

No glitches in the tested code. Yay!
Add negative bounds check for lengths entries in expandToLengths
Add ArrayUtilsTest.testExpandToLengths

Once again, works like a charm.

Watch my next unit-tested piece of code die horribly.
Make EventResult cache arrays 2-D

Nearing the point of fully-user-editable sweeps. Just need some setters
(and a GUI, which will be set up later).