PadStickUse class abstract base

What a stick's two axes are for.

Open, and opening the list alone would have been useless. This was an enum of three, switched over in one method — so a game could not say its stick leans the ship, and adding a value to say so broke every switch in every game already shipped. Opening only the vocabulary would have left an open list with a closed interpreter: a game could name its use and nothing would know how to run it.

So the interpretation moved onto the value. A use is what it does with a deflection, and a game's own use brings its own route — which is why the three below are instances rather than cases, and why there is no switch left to break. base: extend it, do not implement it. A stick use that implemented this would stop compiling the day route gains an argument, and an open type whose additions break its users is not open for long.