GitLab

* CPU: Refactored code to be generic across vector CPU platforms.

Ewald and non-Ewald interactions now share a common code base, templated on
their interaction type.

The vec4 and vec8 implementations have been replaced by a single generic implementation
class which is templated on SIMD type. Currently works for SIMD4 and SIMD8 types, but
can be extended in future to support other types (e.g., AVX-512).

Modified runtime CPU support to lay groundwork for future SIMD types.

Pulled out some vector utility functions (gather pair, reduce),
and refactored the AVX CPU code to make use of them.

* CPU: Fixed coding standards and incorrect header include.

* CPU: Fixed code review comments from PR #2661

* CPU: Fixed CI build issues.

* CPU: Further CI fixes.

* CPU: Fix for unit test failure on MacOS.

Reverted optimised code to go back to a version which is thought to work
on MacOS. The optimisation will be reapplied in future after the failure is
understood better.

o Only reference reciprocal space code works, for now.
o Vector lengths of 4 and 8 implemented and tested.
o Tests pass for Reference and CPU platforms.

o Only reference reciprocal space code works, for now.
o Vector lengths of 4 and 8 implemented and tested.
o Tests pass for Reference and CPU platforms.

Enforce memory alignment to improve performance of vector operations.  Also fixed bugs in an earlier optimization.

Optimizations to CPU nonbonded forces: better load balancing between threads, use linear splines instead of cubic

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

Implemented the Ewald summation method in the reference platform. Preliminary cuda prototype is included.