Clean-up input subsystem

[ataffanel]

Currently the input subsystem is complex and spread all around the client. This makes it very hard to implement new control mode in the client and to use the input subsystem in other programs.

The input subsystem should be revamped to be more self-contained and so to make it easier to work with it.

[Mitteau]

I am working on issue #192 and I completely agree with this commit. I think there are three ways to revamp the system:
1/ isolate blocks of lines in the main.py (and others modules concerned), the simplest way. I use it presently,
2/ create a new file which contains every declaration an function concerned and "include" it (import) in the main.py and others,
9/ create a new class dealing with everything which concerns input suystem (but is that not the aim of the class JoystickReader?).
What do you think is the best way?
BR Jean-Claude

[jonasdn]

Is this issue still valid? @ataffanel @Mitteau ?