Added directory to species() and transitionState() CanTherm input blocks.
Added directory to species() and transitionState() CanTherm input blocks.

This allows the user to specify a directory on disk to look for the
Gaussian input files for a species or transition state. This is useful if
your Gaussian files are not kept next to your input files. For example, I
use this to refer to the reactant and product species in a CanTherm input
file used to generate kinetics.

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