[ADD] im_screenshare : add the mouse tracking libraries
[ADD] im_screenshare : make the mouse tracking work
[IMP] im_screenshare : unifiy the way to send mutations for recording or sharing with one controller. RecordHandler (js side) is the business object managing the mutations, and its children are in charge of displaying the button.
[IMP] im_screenshare : make the screen record works, changing the models, adapt the unique controller and js RecordHandler
[IMP] im_screenshare : create a unique player for both cases (screensharing and screenrecording) + update the js doc.
[IMP] im_screenshare : change all the views and add functional field on im_screenshare.record