lazy evaluation (i.e. don't run tmpl_init_xxx until it's needed)

revise finding residue templates

	perhaps a find_amino_acid vs. find_nucleic_acid vs. find ??

	perhaps if the name is found with a N or C prefix, look it up
	without the prefix?

	what about different force fields (U vs. ???)

what about other PDB residues?

what about differences between amber/leap and PDB?

	POM residues in amber/leap
