GitLab

"truly" random seed being generated from the wall clock upon Context creation.

Added doxygenable comment that Langevin friction coefficient is in units of collisions per picosecond (as opposed to picoseconds), which Sherm and I deduced by reading reference implementation and testing extreme values.

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

1) Added DLL export macros to many classes; enough to get tests to compile
2) Cosmetic changes to reduce warnings in Visual Studio:
   a) change many "for (int i ="... to "for (size_t i ="... to avoid unsigned mismatch warnings
   b) included many explicit static_cast<OpenMMReal>() casts to document places where double->float conversion warnings occur