* Bring the wx frontend more in-line with the rest of the codebase.
* Always default to Unicode APIs on Windows.
* Clean up all include guards and headers.
* Move src/apu/, src/gb/ and src/gba/ to src/core/.
* Clean up include guards and headers.
* Rename `BKPT_SUPPORT` to `VBAM_ENABLE_DEBUGGER` and remove the
`NO_DEBUGGER` define.
CMake 3.25 introduced the CMAKE_MSVC_DEBUG_INFORMATION_FORMAT to set the
/Z flag for MSVC toolchains. Use it rather than modifying the compile
options if possible. We revert to setting the compile options manually
if the CMake version is too old.
* Use add_compile_definitions everywhere.
* Remove unused intermediate target.
* Add ASAN support for MSVC.
* Remove duplicate option definitions.
* Configure MinGW separately from the toolchain
* Move toolchain-specific options to their own files.
* Clean up and modernize the use of toolchain options.
* Use modern cmake LTO support.
* Remove dead cmake code and cmake functions available in upstream cmake.
* Update README.md to remove references to removed build options.
Fabrice de Gans