Better checking for forbidden structures when generating reactions.
Better checking for forbidden structures when generating reactions.

In __generateProductStructures(), the reactants are checked before the
recipe is applied, as there is no point in generating the products if
the reactants are forbidden anyway. Also removed a redundant check of the
product structures from __createReaction() which was already covered in
__generateProductStructures().

faribas/RMG-Py,comocheng/RMG-Py,KEHANG/RMG-Py,faribas/RMG-Py,enochd/RMG-Py,nyee/RMG-Py,enochd/RMG-Py,pierrelb/RMG-Py,nyee/RMG-Py,nickvandewiele/RMG-Py,pierrelb/RMG-Py,chatelak/RMG-Py,chatelak/RMG-Py,comocheng/RMG-Py,KEHANG/RMG-Py,nickvandewiele/RMG-Py