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.