Merge pull request #1 from pklaus/argparse-improvements

fixing ranges in argparse handling
make dwdweather executable
2to3-3.4 -w dwdweather.py
Undoing stupid duplicate 2to3 print() brackets
main() moved to its own function
Fix exception if action for subparsers missing

see http://bugs.python.org/issue16308
StringIO/BytesIO + Decoding before operating on the content
Decoding a binary file before using it as text