* add DefaultCameraController:
* mouse-only navigation
* keyboard modifiers fallbacks for view re-centering (Ctrl+LeftClick) and fast zooming (Alt+RightClick)
* improved double click handling for 3D Object Picking
* moved logic/Timer to the CameraController
* always use TrianglePicking but only activate the ObjectPicker when necessary
* ImageGallery displays images from CameraInit.viewpoints
* support drag&drop of images
* Viewer2D displays and allows basic manipulation of currently selected image