* 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
New version of AlembicEntity always clears itself when setting an url (even if it's invalid/empty). Don't need to re-create the AlembicEntity each time we load a file.
* 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
* optional and only available if AlembicEntity QML plugin is in QML import path
* 3D viewer can load a 3D model and an Alembic file at the same time
* add contextual menu options to unload model/Alembic
* 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
