Fix initial mole fraction normalization!
Fix initial mole fraction normalization!

Previously we divided each term by a different thing,
because we re-evaluated the sum within the loop!

nyee/RMG-Py,nyee/RMG-Py,nickvandewiele/RMG-Py,chatelak/RMG-Py,pierrelb/RMG-Py,chatelak/RMG-Py,nickvandewiele/RMG-Py,pierrelb/RMG-Py