Configurable number of "multiple taps"

[igorsantos07]

Right now, the TT(x) commands to change the layer momentarily or toggle "in case of being tapped multiple times" require at least 5 sequential taps on a key. On my view, 3 taps would be enough, or maybe even two (my IDE has a standard shortcut where I tap shift twice to run something, and it works wonders).

This should be configurable somewhere on the VIA settings, so one can reduce the number of multiple taps to achieve the second function.

This is probably related to #68 and #160 as well.

Edit: seems tangentially related to #229?