Add support for compilation on x64 toolchain (x86 cl.exe was running out of heap space in vm.cpp)
Also took the opportunity to change compile optimisation from /Ox to /O2, as /O2 provides better optimisation than does /Ox
Also, we shouldn't be explicitely setting compiler tool defines (__cpp_lib_bitops), so remove that from types.h
- Added support for current default toolset, explitly specified c++17 standard and 8.1 win sdk.
- properties were defined via `common_default.props` and `common_default_macros.props`
Note: There are 2 files because some properties need to be imported before `Microsoft.Cpp.Default.props` , but other common properties can be imported after but they require marco defined in `Microsoft.Cpp.Default.props`.
- Added hidapi and libusb project files to repository to simplify msbuild changes.
Also renames "AudioThread" to "AudioBackend". The new name is more
descriptive of what the class really is responsible for, since the
backends are not responsible for managing the audio thread.
NOTE: Right now only XAudio2 is supported
