[ck2cti] Allow arbitrary reactant stoichiometries
[ck2cti] Allow arbitrary reactant stoichiometries

There is no reason to disallow more than 3 reactants

Heathckliff/cantera,imitrichev/cantera,imitrichev/cantera,Heathckliff/cantera,Heathckliff/cantera,imitrichev/cantera,Heathckliff/cantera,imitrichev/cantera,Heathckliff/cantera,imitrichev/cantera,Heathckliff/cantera,imitrichev/cantera