- added toFixed() filter
- added custom arrow color for distance measurements (based on
youmagine color scheme)
- added (but commented out for now) example image plane
- added toggling between distance measurements and annotation adding mode
(work in progress)
- experimented with overlay notes (content editable: yuck)àààààààààà
- small changes to overlay notes:
 * minor bugfix for title editing
 * styling changes
 * experimenting with deep change watchers

- added in memory storage for distance measurements
 * not possible yet to recal previous measurements / display
them