GitLab

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

- 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.

Implemented setting random seed for reference platform, as well as adding it as an option to BrownianIntegrator and AndersenThermostat.

Added 'return platform' to registerReferencePlatform() -- VisualStudio complained about no return value
Added #include "../sfmt/SFMT.h" to SimTKOpenMMUtilities.h to get 'uint32_t' declaration