binding transition for reaction schemes
A subclass of RSreac implementing a simple mass action scheme where nreac reactant particles combine to produce nprod product particles. The forward rate is given by k-f (mol-HAT()-nreac /s) and the reverse rate by k-r (mol-^nprod /s).
Thus, for example, for the reaction A+B <--> C, nreac=2, nprod=1, and the forward rate would be [A][B]k-f transitions per second and the reverse rate [C]k-r transitions per second.