Added Wolff cluster algorithm for XY model with disorder couplings
Added Wolff cluster algorithm for XY model with disorder interactions (TDisorderXY)
Fixed an error with GrowWolffCluster
Reordered graph plotting, to ensure plot output in the event of linearized graph failure
Slight modification to XY chain hamiltonian, for convenience of cluster algorithm simulation. Also, added cluster simulation for XY chain TMultiXY