Zooming sticky at 1:1

[jonas.kirilla]

Make zooming sticky at 1:1, when using the mouse wheel. (Much like windows stick to screen borders, as if magnetic.)

Even if there was a scale indicator with a clear visual cue for 1:1 it's easy to overshoot.

(Of course the scale doesn't matter most of the time, and keyboard shortcuts, like "Original size", are well worth learning.)

[leavengood]

Implemented in hrev42311.