Allow certain types of ChemkinError to be ignored with a warning.
Allow certain types of ChemkinError to be ignored with a warning.

This allows you to just skip a reaction by doing:
    raise ("Skip reaction!")

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