I was not able to generate the gestures "pinch" and "expand" on Kobo Aura.

While debugging ```GestureDetector:panState(tev)```  I saw that the TRACK ID never had -1 values .
So back to debugging ```input.lua```.

Now the Kobo Aura can pinch and expand.
Merge pull request #403 from Markismus/MultitouchKoboAura

This should fix the pinch and expand gesture on Kobo Aura