added general bng module with beginning of generate_equations
added general bng module with beginning of generate_equations

johnbachman/pysb,neurord/pysb,d-fan/pysb,alubbock/pysb-legacy,alubbock/pysb-legacy,alubbock/pysb,LoLab-VU/pysb,neurord/pysb,d-fan/pysb,LoLab-VU/pysb,alubbock/pysb-legacy,spgarbet/pysb,spgarbet/pysb,spgarbet/pysb,alubbock/pysb-legacy,johnbachman/pysb,d-fan/pysb,pysb/pysb,neurord/pysb,jmuhlich/pysb