[Cython] CmdLine.py refactoring

[Stefano]

Hi,

I've cloned GitHub repo and started working on it. First, I'm rewriting 
Compiler/CmdLine.py to use the optparse/argparse module. Then I'll try to 
address the Bugzilla ticket mentioned in the source file.

Question: optparse has been deprecated since 2.7 (which adopts optparse 
module). So, which one to choose? Old one, or new one? Or should I work on a 
fallback system?

--SKS