captouch api change: moved from `pads` to `position`

pads is deprecated and removed. position is deprecated as well but won't be removed until flow3r v2.0. To use the new normalized pos api, use .pos.imag > 0.3 instead of .position[1] > 10000 (conversion factor about 1/35000). Since this API does not exist on flow3r v1.3 yet we opted for this currently more universally compatible option here.

We can change the commit message to be more succinct if you prefer.