- minor adjustments to visual editor:
 * style and controls
 * attempting to refine context menu
- re added keyboard shortcuts: (towards closing task #45)
 * now uses mousetrap.js lib
 * not configurable just yet
 * added basic implementation for keyboard manager
 * added settings menu entry: while not settable , the shortcuts are listed there
 * experimented with (related) commands system implementation
- various improvements to the camera systems, and some minor cleanups in visual Editor