Merge pull request #140

0214524 added mikezackles / Zachary Michaels gpg key (Riccardo Spagni)
Merge pull request #141

b92a8b5 fix CMake for multiplatform versioning (Riccardo Spagni)
Default to static linking on both MSVC and MINGW
Remove unused CMake function
Ignore another warning to make mingw happy
Hack to allow toolchains to pass flags to mingw
Set the boost thread api for mingw
Change to -static gcc flag
Hack to add pthread to link libraries on mingw

This should link winpthreads.  We really shouldn't be passing these this
way, but that seems to be the existing solution, and it works for now.
Remove unnecessary else
User setting to turn LTO on and off

This isn't currently working on mingw
Change Windows include to windows

mingw is case sensitive
Correct includes for mingw in slow-hash

This needs testing
More preprocessor fixes for slow-hash
Another preprocessor fix (difficulty.cpp)
msys2 32/64-bit toolchains
Force CMake to link the runtime statically
Use unwrapped binutils for msys2

The default binutils wrappers are built without plugin support.  This will streamline the build process until we decide to start supporting LTO.
Fix march flag for 32-bit build
Move toolchain files