* Added bitexact implementations of _BitScanForward64 and _BitScanReverse64 for VS2019 32-bit builds
* Added bitexact implementations of _umul128 for VS2019 x86, arm, arm64 builds
* Implement mul_overflow for VS2019 arm64 builds
+ implement mul_overflow using __umulh (msvc/clang results: https://godbolt.org/z/smRwA7)
* Added Win32 for VS2019 to .appveyor.yml
* Update amalgamated headers (fix x86 builds with VS2019)
* Fallback should use our scalar code.
* parse should have a nicer error message.
* Making it so that "minify" can use different architectures.
* Let us change the minifier competition so that it tests all implementations.
* Documenting the untaken optimization opportunity.
Co-authored-by: John Keiser <john@johnkeiser.com>