- handle shift-key to move slides forward and backward

...g/bigbluebutton/modules/present/events/NavigationEvent.as

...uebutton/modules/present/ui/views/PresentationWindow.mxml

...button/modules/whiteboard/WhiteboardCanvasDisplayModel.as

...g/bigbluebutton/modules/whiteboard/models/Presentation.as

...igbluebutton/modules/whiteboard/models/WhiteboardModel.as

...uebutton/modules/whiteboard/services/WhiteboardService.as

...bluebutton/modules/whiteboard/views/WhiteboardCanvas.mxml

...utton/modules/whiteboard/views/WhiteboardTextToolbar.mxml