- added basics (and not so basics) of notes/annotations overlay system
 * read from a json data structure (for now hard coded for testing) that
can be passed to the viewer
 * added custom element "overlay-note" to wrap this annotations up nicely
 * added code to link their on -screen updates to the internal clock
of the three-js element
 * added demo styling
- experimenting with fine tuning annotations:
 * experimenting with camera zoom in on annotation
 * "" with additing orientation to annotations

- cleaned up zoomInOnObject helper, needs more tweaking
to zoom in on annotations etc
- minor adjustments and fixes for annotations :
 * overlay-note now fires an event when tapped
 * moved zooming in on note to on-tapped/toggled method
 * minor css adjustments
 * experimenting with modifications to camera zoom in system
- fixed issues with positioning (in 2d) of overlays
- rewriting zoomInOnObject helper:
 * previous logic & computations were actually false (
distance from camera instead of distance from object etc etc)
 * focusing in on annotations for example (off-center items in general)
now works correctly
 * proximity to target object is now more coherent
 * needs more cleanup (proximity param should be distance (from target))
etc
- further adjustments of the zoomInOn effect:
 * swapped out distance (vector) compare (to determine whether zoom in is needed
at all) with testing for close approximation of vector components
 * slight code cleanup
- modified overlay note behaviour for more intuitive use:
 * if note is closed, and user selects its number , overlay opens
and is focused on
 * text content of note can be opened/closed independantly from focus
- added temporary fix for annotation 3d poi not available
after an object has been unselected
- added ability to only display annotations for a given part
 * for now implementation is hack-ish at best until data structures are
better defined
- moved out hard coded demo data for annotation into demo.html
 * cleaned up annotations related code
Merge branch 'annotations'