Remove of prefix _ for python file

[jmkerloch]

@azarz @lgrd All python files are prefixed with _.

Is there any reason for that ?

I'm afraid this kind of naming could be misinterpreted by some parser. It may be better to remove all prefix.

[azarz]

It was because those files are "internal" / "private", and the methods in those modules shout not be imported when one writes

from r2gg import *

However if this causes errors in parsers, we can remove this prefix.