- fleshed out a much more detailed assembly instruction example:
 * based on top part of 3DR-tiki
 * just text, but trying to highlight automatable parts, identifiers, boms
- fixed orientation/up vector issue in visual representation of connectors
- added method to toggle text display for distanceHelper
- further fleshing out of example instructions/assembly:
 * added connectors to all the correct positions / orientations
- improved handling of connectors:
 * added visual display of connectors
 * all loaded meshes + connectors now correctly get attached to a dummy
 object, one per assembly step, that gets hidden/removed from scene when
 switching between steps
- started experimenting with different representations (visuals) for different
 actions :
  * helix for "screw in / out"