Add shebang

The highest Python version supported is Python 2.4.
Source modification needs to be performed.
chmod Main.py 0755
Use hashlib instead of md5 library

md5 library is deprecated since version 2.5.
Update Shooter.py for more Pythonic code and Python 3 compatibility

The script can now run on Python 2 (>=2.5) and Python 3 (>=3.0)
PEP8 style warnings free
Merge pull request #2 from m13253/master

More Pythonic code & Python 2 / Python 3 full compatibility & PEP-8 styled format