changed mixed_nash defaults to match the command line ones
Major bug fix in RD for role-sym games where roles have != #s of strategies.

RSG.randomMixture() was returning non-zero probabilities for non-existant
strategies. This means that any replicator dynamics runs with random restarts
(the -p command line argument) on games with multiple roles that have different
numbers of strategies for different roles are suspect and should be re-run.