Overhaul the tests to get more predictable behavior.

The most important change to the SymmetricLinearGame tests is that we
now check the condition numbers of the generated games. That prevents
most of the numerical trouble experienced before, and solves a few
open TODO items.

A RANDOM_MAX constant was introduced, and incorporated into the fudge
factor for the absolute tolerance used in tests. That contributes to
fixing the open TODO items as well.

The test code itself is pretty ugly now, but it can be fixed once they
all pass reliably (there's still a Lyapunov-like test failing).