Add scale parameter to zoom animations

[MickL]

Currently the zoom animation fades from 0 to 100% and scales from 0 to 100%. The scale from 0% creates a very mighty effect which I would like to settle down. I would like to define the start-scale for zoomIn and the final-scale for zoomOut to make the effect more gently. E.g. from 0.8% to 1%.

For comparison: Netflix zooms in the full page gently when starting a video. This is currently not possbile.