Added cantherm.states module for working with molecular degrees of freedom.
Added cantherm.states module for working with molecular degrees of freedom.

Currently it contains functions for correcting energies and generating
vibrational frequencies after projecting hindered rotors out of the force
constant matrix.

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