Enhanced the setup script for Cython extensions.
Enhanced the setup script for Cython extensions.

The script now need command line argument(s) to build the extension.
This will let users select wich extension to build.

If no argument is given on the command line, a help message is displayed.

Khroki/MCEdit-Unified,Khroki/MCEdit-Unified,fhfuih/MCEdit-Unified,fhfuih/MCEdit-Unified,Khroki/MCEdit-Unified,fhfuih/MCEdit-Unified