GitLab

* Unified lots of parallel computation code between platforms

* Unified test code between platforms

* Eliminated duplicated timing code

* Optimize CustomNonbondedForce.updateParametersInContext()

* Optimized uploading changed values to GPU

* Optimized updateParametersInContext() for lots of bonded forces

* Optimized updateParametersInContext() for CustomExternalForce

* Optimized updateParametersInContext() for NonbondedForce

* Code changes for HIP platform

Continuing to implement new CUDA platform: CustomBondForce, CustomAngleForce, CustomTorsionForce, CustomExternalForce, CustomCompoundBondForce

Moved SFMT into libraries folder, and restructured it to allow multiple independent random number generators

Modified the API for lots of classes so that the number of particles/bonds/etc. need not be specified in the constructor.

Continuing to implement ReferencePlatform (implemented kinetic energy calculation and LangevinIntegrator)

Created a test case for StandardMMForceFieldImpl's findExclusions() method.  Fixed some bugs that it found.  Created a CMake script and configured it for building and running test cases.