Squashed commit of branch 0.6.34

* anonymine_engine.py (game_engine.init_field2):
    - Implement timeout on Windows 10+
* test.py (_game_hash):
    - Ignore WindowsError
* test.py (create_cfg):
    - Choose a safe path for the temporary config file
* anonymine_engine.py (load_cfg), anonymine.py (main):
    - Check file safety in `anonymine_engine.load_cfg`
    - Handle windows-beta/cursescfg "symlinks" in a sane way
* installtools/install-cfg, and ^^^ above thing ^^^:
    - fstat the opened file instead of the path to avoid
      race conditions
* anonymine.py (main):
    - Get traceback on Jython if something goes wrong (#2)
* test.py (test_multiprocessing), installtools/test-multiprocessing.py:
    - Test that the multiprocessing module is workin in test.py
* README.md, doc/INSTALL.Haiku, doc/INSTALL.SerenityOS:
    - Some updates
* windows-beta/setup.bat, doc/INSTALL.Windows.txt:
    - Added a batch script to initialize highscores and install
      windows-curses
* doc/INSTALL.txt, doc/INSTALL.advanced, doc/INSTALL.advanced.staged:
    - Remove INSTALL.advanced.staged, the whole install system
      should be replaced at some point