Fix synchronization with 3D camera selection when the corresponding image has not been instantiated in ImageGallery (outside visible viewport).
* SortFilterDelegateModel: add "find" method
* ImageGallery
* move passive selection logic out of the Delegate as it's created only when visible in the GridView
* use SortFilterDelegateModel.find to get item index based on selected "viewId" and set GridView's currentIndex
* bugfix: in latest PySide2 versions, application palette is not properly applied to all QtQuick Controls 2 components. Force this by exposing QApplication palette and bind it to the root ApplicationWindow.
* rename all "palette" ids to "activePalette" to avoid clashes with "palette" property on QtQuick Controls 2
* use parent component palette when it makes sense to propagate active/disabled style (instead of always using Active SystemPalette)
* create two separate drop areas when adding images to the project (add images / augment reconstruction)
* add sfm augmentation in graph after intrinsics have been built
* add the notion of a current SfM node in the Reconstruction
* retrieve views and poses from this node when selected or when its status changes
* use this information to display a status on Images in ImageGallery
* add WorkspaceView that contains Meshroom main modules (ImageGallery, 2D/3D viewer)
* add Panel component to standardize UI modules layout
* ImageGallery:
* add images basename on image delegates
* add explanatory placeholder when no image has been added to the reconstruction yet
* 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
