GitLab

Created #define for LOCAL_HACK_PI to sidestep bug on Windows cuda compiler which ignores "static const float ..." variables.
In files kCalculateCDLJEwaldFastReciprocal.h, kCalculateCDLJForces.h and kCalculateLocalForces.cu.

Lots of new optimizations in ParsedExpression.optimize().  Also optimized CUDA evaluation of expressions.

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

Created a CudaPlatform property for specifying whether CUDA should sync or spin loop while waiting for results

- MingW, where "WIN32" is set by CMake but the compiler is not Microsoft's (should use _MSC_VER) in that case, and 
- in gcc 4.4 which is fussy about some issues that earlier versions were silent about, such as passing a string constant to a "char*" rather than a "const char*".
I also fixed a syntax error in CMakeLists that showed up in the OpenMM workshop for some unknown reason.

Brook is not currently building correctly; I think it has not yet been fully converted to the getTime() interface needed for variable step integrators.