Revert "Don't change Zoom when toggling dynamic colors"

This reverts commit d86ac93ea0ca53fd3d40d513f030b678b8153489.
Add missing member declaration
Make toggling dynamic colors less invasive

- preserve zoom and selected/focussed session state and highlighting
overlays
(drawResultMarkers() calls deleteResultOverlays(), which is too
destructive)
Merge pull request #4 from thomasstache/markercolors-by-value

Merge Make toggling dynamic colors less invasive