Interface the input system

[Gamabunta57]

As the other architectural tickets, the goal is to provide an simple abstraction layer over the input system from SDL.

The goal of the interface is to provide an API that can:

• initialise if needed and free memory if needed
• propose an API to do some basic event checks like "isDown", "isUp", "isPressed", "isReleased" for buttons of keys
• propose an API to get information from analog inputs with
  • isInDeadZone
  • setDeadZone
  • getValue?
• #later: propose an abstraction to have an API that gets analog inputs but as logical input like buttons
• #later: propose an abstraction to have logical inputs behaving like analog inputs (saw that in Unity but, is it useful?)