Add option to make minus activate Share instead of Touchpad

[s5bug]

[s5bug]

@d3xMachina I've updated this to master if you would be willing to take a look

[d3xMachina]

I have not merged this since this is too niche (swapping both minus with share and plus with home would be acceptable though). I let it open just in case anyone is interested. Ideally a feature to remap any button would be ideal (I made one a while back but there was still unfinished changes and since then the code changed a lot...).

[s5bug]

I can maybe try sometime over the next week to figure out something for arbitrary button remapping...