Update PDepReaction to add label, remove thirdBody attributes.
Update PDepReaction to add label, remove thirdBody attributes.

This reflects the same changes in the base Reaction class made as part of
this refactoring.

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