* make Drag/DropArea overflow on the attribute's label to be more tolerant when connecting attributes
* add visual feedback when hovering interactive areas
* tweak spacings between attributes
* fit when the underlying graph has changed (new/open project)
* add 'F' shortcut to fit
* trigger fit after UI has been fully initialized (correct sizes)
* increase EdgeMouseArea thickness for easier picking
* EdgeMouseArea: propagate modifiers on pressed
* increase edge visual thickness when hovered
* add edge contextual menu on right click
* Alt+RighClick shortcut to delete an edge
Handle nodes move and auto-layout on Python side by using GraphLayout and MoveNodeCommand.
* Node QML component relies on underlying core.Node object's position
* MoveNodeCommand is called after a Node has been dragged
* partial/full auto-layout for specific graph operations (Duplication, Augmentation...) are now part of those operations
* serialized position in node data allows to properly restore nodes coordinates on undo/redo
* remove all layout/node moving code from QML
* fix reference to non-existing slider.value
* convert values to string to avoid e+XX notation on large numbers
* fix number of decimals based on stepSize to avoid floating point approximations
* display and allow to upgrade incompatible nodes after project loading
* add a ToolButton in main toolbar to open CompatibilityManager in case of compatibility issues
handle this low-level operation engine side
* fix ListAttribute children links duplication
* handle CompatibilityNode duplication
* move corresponding unit test in test_graph.py
* [ui] add DuplicateNodeCommand
* fix ListAttribute => ListAttribute with children (was breaking multiple simple connections to a ListAttribute)
* add missing case ListAttribute => Attribute
* 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)
* allow duplication of one node/all nodes following a node
* actions available from Node contextual menu and Alt+Click on node for multi-nodes duplication
