Added events for middle and right mouse button press and drag to flower library and flower sample

I did not change the way the Left Mouse Button works. I added the following events : 
Event.RIGHT_CLICK, Event.MIDDLE_CLICK, Event.RIGHT_MOVE (RMB pressed + mouse moved), Event.MIDDLE_MOVE(Middle Mouse Button pressed + mouse moved)
Clicks return a down field, moves return a down (always true), and x and y field.
Added a rdown and mdown field to InputMgr.pointer