Add swipe gesture to switch between tabs

[nettnikl]

Hi! I know you're busy currently, but as another suggestion:

What

Swipe to the left to switch to the next tab to the left, and similar for rightwards swipe.

How

Not sure, but i think this is possible in some fragment tabbing libs, not sure which one is used here. If possible, not really the gesture listener, as this would feel weird (do full swipe, then see animation); instead you can pull the next tab progressively into the frame, and abort if necessary. Not sure how to describe.

Why

Makes usage quicker, e.g. when copying from one location to another.