If unexposed attributes (ie. attributes that are located in the lower
side of a node, and hidden by default) are connected, they are meant
to remain visible even if the lower part of that node is hidden.
This was working fine for any attribute that was not a `ListAttribute`,
as the check was made on whether the attribute's value was a link to
another attribute. For `ListAttributes`, whose value is actually a list
of values, this was not working as nested links were not checked.
Instead of relying on the `isLink` property, we now use `isLinkNested`:
for regular attributes, this is equivalent to using `isLink`, but for
`ListAttributes`, the full list of values will be checked.
The color selector in the Graph Editor provides a quick way to color nodes with predefined palette of colors.
Added Command to allow the Coloring to be undone and redone using QUndoStack
Provide a way to control how to handle node compatibility issues
when loading a Graph with the `strictCompatibility` parameter.
Introduce a new error type, GraphCompatibilityError, to be raised
when loading a Graph with compatibility issues with strictCompatibility enabled.
Default camera up should be accurate and consistent with camera view center.
Default camera up vector is not refresh or checked when default camera view center is set.
With the Sequence Player always enabled by default, the `fit()` function
must be triggered at the right moment, and only once the layout has
been correctly initialized; otherwise, zoom factors may become negative
and the images will not be placed correctly in the viewer.
Changes in the orientation tag must be handled independently from the
state of the zoom factor.
The callbacks of `childrenRepeater` (which was used to "fill"
`ListAttributes` with children) were not correctly set. Their prototypes
were missing the `index` argument, meaning that instead of being
provided with the child attribute that was added or deleted,
they were provided with its index in the model.
The added children attributes were also instatiated as empty attribute
pins that were still visible, thus increasing indirectly the spacing of
the initial pin.
