This reverts commit dd464af.

Strictly speaking, reverting this commit fixes the issue with no side effects but it is not completely clear why that code did NOT cause this issue in the first place. Other solutions might be worth looking into.

Explained fairly well in Nomagno#27
The "edit" section was just because releasing accel makes the kart not consume nitro, nothing to do.
This issue also affects binding look back, brake, or any other digital action to an analog axis That has its resting position as fully negative, and its fully pressed position to fully positive.

Steps to reproduce:
With a controller, bind e.g. "look back" to analog right trigger, or "nitro", whatever really. Once you press it once, it is now (almost) impossible to get the game to stop doing the action. The only way is to get the trigger to be EXACTLY 0 by pressing it exactly halfway, which isn't that hard but is a completely broken way to play.

Agreement

By creating a pull request in stk-code, you hereby agree to dual-license your contribution as
GNU General Public License version 3 or any later version and
Mozilla Public License version 2 or any later version.

This includes your previous contribution(s) under the same name of contributor.

Keep the above statement in the pull request comment for agreement.