Windows Installer : Python3 + 64bit

Upgrade of windows installer build system:
- revisions.txt supports "local" to point to local working directories
- msys2 ucrt64 64b runtine
- use requirements.txt
- most python packages from msys2 repo
- still use pip/wine for other python packages
- some cleanup in Makfile code, removing dead code
- CANopen, Modbus and OPC-UA not included... to be continued.

import os

PATH = os.environ["PATH"]
instdir = os.path.dirname(os.path.dirname(os.path.realpath(__file__)))
os.environ["PATH"] = ';'.join([
    os.path.join(instdir, "msys2", "bin"),
    os.path.join(instdir, "msys2", "usr", "bin"),
    os.path.join(instdir, "msys2", "mingw64", "bin"),
    PATH
])