GitLab

Began implementing new mixed precision model that does integration in double precision and force evaluation in single precision

Variable time step integrators correctly report the size of the last step taken.  Also improved accuracy of integration unit tests.

Eliminated having CMake run programs to check for CUDA and OpenCL compatible GPUs.  They mostly just caused problems.

Tony's changes to error handling in the CUDA platform so it throws exceptions instead of calling exit()

Removed debugging code