* new footer that displays the number of images / allow to change thumbnail size
* smaller sourceSize for thumbnails (faster to load)
* avoid Nan scales in Viewer2D when no image is loaded
* add Rotation/Scale controls
* add controls to disable default items (grid/locator)
* add drop support to load external 3D models
* add "View All" action in contextual menu to fit to scene
* automatically propose to load the reconstructed mesh when available
* ImageGallery displays images from CameraInit.viewpoints
* support drag&drop of images
* Viewer2D displays and allows basic manipulation of currently selected image
