* Retarget Visual studio tool chain to v142
* add ARM64 option to wintest.bat
* add windows/arm64 target to appveyor for CI
* add arm64 targets to visual studio solutions
* add cross compile option to wintest.bat
* Fix missing SET in wintest.bat
* update auto-generation scripts for msvc and update project files
Tagged as deprecated for years, never imported by `<sodium.h>`, and
intentionally never documented.
`edwards25519sha512batch` was just around for ABI compatibility
with NaCl, but no projects seem to be using it.