GitLab

o Added C12 shift term, to match GMX.
o Added tests to compare energies and forces directly to GMX, with and without exclusions.
o Modified set/get LJPME parameters to look similar to electrostatic equivalents.

Platform specific header files get installed.  This allows plugins to be built with just an OpenMM installation, not a full source tree.

NonbondedForce sometimes included energy terms that weren't appropriate to the specified force groups

All platforms now handle nonbonded exceptions in a consistent way (they ignore cutoffs and periodic boundary conditions).  Also started OpenCL implementation of CustomHbondForce.

The differences in the Ewald energies between the Reference and Cuda platforms were traced to roundoff error in the 
computation of the Vdw and Coulomb ixns for the short-range energy contribution (verified using double precision in the sum); the vdw and Coulomb terms are now accumulated separately and then added to the total energy 

In Ewald SR portion of code, the LJ contribution to dEdR was missing a factor of (inverseR*inverseR)

All energies existing in Preview Release 3 now run on the GPU, new Ewald energy terms still use Reference implementation