Multiple changes:
- actions are now available unconditionally, but only work in the right
state. This mirrors other actions.
- instead of adding actions manually, they invoke the action on the
GtkCellAccessibleParent interface.
Tests have been updated to reflect the changes
Various tiny semantic changes in here.
The big fix is that we consider every cell as visible and as showing if
the treeview is mapped.
This was also fixed in the tree dump test.
This drops the AtkText implementation, and also strips handling
of children out. Instead of listening for enter/leave/press/released,
just listen for state changes on the widget.
Selection count is tested via assertions and can be inferred from
looking at the number of selected children.
And I'd like to reduce the output of the tests. We're outputting way too
much anyway.
