extractScale helper function moved to Affine3DHelpers in spimviewer.
Merge remote-tracking branch 'origin/multiviewtracker' into multiviewtracker-contrib

Conflicts:
	src-plugins/MaMuT_/src/main/java/fiji/plugin/mamut/detection/SourceSemiAutoTracker.java
	src-plugins/MaMuT_/src/main/java/fiji/plugin/mamut/util/SourceSpotImageUpdater.java