add right click events

Add rightClick, rightClickStage, rightClickNode, and rightClickNodes
events
Merge remote-tracking branch 'origin/master' into captors-mouse-right-click
Merge remote-tracking branch 'origin/pr/306'

Conflicts:
	examples/events.html
	src/captors/sigma.captors.mouse.js

Also ported some modifs from PR #307 to right click related code.