Dynamic Key binds itself on game launch

[S1aeh]

When Dynamic Key is set to 'Not Bound' (config value = -1) it gets set to 'scancode.0' (config value = 0) next time the game is launched, which sends empty commands when left-clicking.

Steps to reproduce:

1. Set Dynamic Key to 'Not Bound' in the in-game config
2. Save config and exit the game
3. (optional) Check that Dynamic Key equals -1 in the config file
4. Launch the game
5. Dynamic Key will now be set to 'scancode.0' in game and 0 in the config file.

[inglettronald]

Yeah I was looking into this and saw that cloth's demo does the same thing as me for their keybind options, not sure what the intended creation of that option is supposed to be...