[Screen Geometry] fix run time error (+1 squashed commit)
Squashed commits:
[29ac0fd] fix wrong merging (+1 squashed commit)
Squashed commits:
[0a0d093] properly call Add/Remove ScreenChangeCallback native function, by counting the javascript listener number (+2 squashed commits)
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[6e1c7c5] Change the screen geometry event handler to use node.js EventEmitter
move Screen functions from App to seperate Screen class
[23332bf] Implement "Generic" Event listener, with application on Screen Geometry events listener (+1 squashed commit)
Squashed commits:
[372c9bd] add App API to get screen(s) information
Merge pull request #2178 from jtg-gg/screen

[Screen Geometry] API for listening to Screen Bound, Display add, Display remove events