First version of retrocompatibility, allowing to load files referencing removed or type-incompatible attributes.
* add node_factory to centralize node instantiation
* discard invalid attributes (i.e. not part of the node description anymore or with incompatible value type) when loading a file
* raise on unknown nodes
* add 'core.exception' module to declare Meshroom's exception types
* add 'sfmPipeline', 'mvsPipeline' and 'photogrammetryPipeline' instantiating nodes in an existing graph
* rename main function (creating a new Graph) 'photogrammetry' + create a Publish node if 'output' is specified
* 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
* move LiveSfmManager.stepCreated to Reconstruction.sfmAugmented
* add utility methods in Reconstruction to get all images/views used in the graph
* ui: perform local auto-layout on sfm augmentation on created nodes
* 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
* keep an internal reference to the "main" CameraInit node an update it according to graph modification
* expose viewpoints model as a property
* TODO: handle multiple CameraInit nodes
* extract UIGraph from Reconstruction: base class that wraps a core.Graph, without knowledge of photogrammetry pipeline
* ChunksMonitor: watch NodeChunks status files for external changes to keep UI updated even when the graph is being computed externally
* Reconstruction inherits UIGraph with photogrammetry specific features
* add methods to add images to the reconstruction (DropEvent or urls)
* explicitly call CameraInit's buildIntrinsics method
* update CameraInit with resulting views and intrinsics
First functional UI that allows to visualize, modify and execute a graph locally.
* use QtQuick Controls 2 + Shapes (Qt >=5.10)
* main menu to save/load a graph
