Moving to Python to make Windows build scripts more maintainable.
It's intended to be a drop-in replacement, so it should be possible to just switch `.\build-deps.cmd` to `python build-deps.py`, keeping exactly the same arguments and behaviour will be the same.
`build-deps.cmd` is deprecated, but not yet removed, but will be shortly after more testing.
Other batch files will be migrated to Python shortly after too.
To speed up the process. Previously we were using `/m` which build different targets in parallel, but not .cpp files. So rocksdb could have been building for 30 mins because of this.
* Make possible to invoke run-cmake.bat, build-ifcopenshell.cmd (now bat), install-ifcopenshell.cmd (now bat) directly from File Explorer or command prompt without VS env vars set, if BuildDepsCache file exists, by utilizing CMake's --build functionality. Do not delete CMakeCache.txt always now in order to keep the build options consistent.
* win/readme.md tweaks + make the line width smaller
* Windows batch files: use the last modified BuildDepsCache. Show an error if GEN_SHORTHAND does not exist.
Andrej730