- Removes files for package building to avoid PyInstaller package beviour.
- Removed __main__.py and run_as_subprocess.py for now, calling Python from path is not an acceptable way to mitigate the relative import issue.
- Renamed pyinstaller.py to pyinst.py to avoid the script being executed when "python -m PyInstaller" is ran.
- Adds Python 3.8 compatible command-line options to pyinst.py
