Function to recalculate FTO using custom settings #71
Description
FTO is currently computed right after import. It is done conservatively: only for turns in 10 second stretches that clearly are dyadic (exactly 2 participants). This makes sense as a cautious default.
However, sometimes users may import a file and want to keep non-speech tiers (e.g. gaze in IFADV). In that case they should be able to tell scikit-talk what tiers to base the FTO calculation on.
So we need a function for (re)calculating FTO that takes as input a list of (two) participants and applies the FTO calculations only to turns that belong to those participants.