Make sure CPU Generalized Born interactions work
Possibly related to Berk's issue with constraints in particle decomposition. For this issue we should mainly make sure the GB kernels work.
Fixed GB interactions for release-4-6
Release-4-6 was not using the correct GB kernels,
but the non-GB electrostatics cutoff kernel. In addition,
the accelerated kernels unrolled more than a factor 2 had
a bug that caused a small error in the forces. Both these
issues have been fixed, and the GB results now match
Note: The GB radius calculations are still only done
in C, but the accelerated options will be re-enabled in
a pending patch (separated for clarity).