Fixed data race condition in Code/GraphMol/MolAlign/testMolAlign.cpp

Hi Greg,

there was no fault in your code - I was just too quick in copy-pasting
the MMFF multithreaded and I did not realize that refMol properties
were being overwritten by multiple threads because I did not make
a local copy in each thread.

Cheers, p.

- Fixed a bug in Code/GraphMol/MolAlign/testMolAlign.cpp which caused
  data races in the multithreaded test
- Removed a spurious #include in Code/ForceField/Wrap/ForceField.cpp
- Restored caching in Code/GraphMol/Descriptors/Crippen.cpp