Revert "Changed the random generator to use a faster one"

This reverts commit d11ddeef0a4435e4bd267f1254b92ddbec0e8d27.

Speed improvement was not real
Revert "Speed improvement for  step in dimorphic population by getting just one"

This reverts commit 1e28e4d02cc0fa57eafc632e9a724e232bf90520.
Random uses Well19937c