Adds verify_chiral_consistency_of_core to verify cores quickly

[badisa]

• Can be slow to construct a SingleTopology object just to determine if the endstates are correct given a certain core, this PR separates out the construction of the end state potentials for the potentials necessary to check the chiral endstates (bonded, chiral atoms and not used currently but also chiral bonds).
• One of the reason this is slow in practice is AM1BCCELF10 (AM1 + Omega), this avoids the need to generate charges
• About 5x faster to call verify_chiral_consistency_of_core with smirnoff_1_1_0_sc.py as shown in https://gist.github.com/badisa/466f73d6045f16454c16239c2bb11096

[badisa]

This still only makes it about as fast as atom mapping, so may not be fast enough. Potentially removing chiral bonds could make it faster, but not sure that would make much of a difference.

[badisa]

25% of the cost of this is the match_smirks method: https://github.com/proteneer/timemachine/blob/master/timemachine/ff/handlers/utils.py#L35