- it works !
- improved/ fixed issues laser outline detection:
 * added dilate pass to have a better continuous outline
 * slightly adjusted initial threshold
 * migrated parameters out from the extractLaserLine method for
future easier fine tuning
 * minor code cleanup/ removal of useless junk

- tweak camera capture, "fixed" huge memory leak
 * experimentally found out go value for emptying camera buffer
 (there was no difference between laserOn and laserOff )
 * at least temporaly switched to custom readSync method of
node-opencv (custom fork for now)
 * added manual garbage collection
 * those last two steps are ESSENTIAL, otherwise, memory consumption is
> 10 mb per slice !

- added reloading of last scan file at start
 * gets dispatched to client side for display: do not have
to redo scans forcefully anymore
 * added handler code client side

- added computation and display of scanning time (client side)
- cleanups in the various module : removed clutter etc

- added extra delay to laser on/off toggling as it is slooow
 *  tentative exploration of faster i/o for the arduino side

- migration to new "pointCloud" classes for the client side