Remove deprecated functions for testing if birads are singlet/triplet.
Remove deprecated functions for testing if birads are singlet/triplet.

We no longer use birads for singlets in the new style adjlist; instead they are
denoted as lone pairs.

Also remove changeTripletSinglet function, as it should be converting radicals
into a lone pair as stated in https://github.com/GreenGroup/RMG-Py/issues/282

Right now, remove all these functions until they are actually needed (these
functions are currently unreferenced elsewhere in the code).  When they are
needed someone can write them again from scratch.

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