I also changed qHash(modelNode) to modelNode.internalId().

Task-Nr: QTCREATORBUG-3387

Introduce node hierarchy and move nodes to a separate file.
Introduce reference nodes that point to additional symbols and
symbols within the symbol tree (make deeply nested linked list
elements visible as array elements). Properly name container
elements as array elements 0..n. Fix pre-expansion of complex
dumpers.

We create a special sidebar item for the item library that contains a
ToolButton.

The ToolButton manages the imports for components.

If an import changes we have to delete the cache for the meta info.

Reviewed-by: Kai Koehne

Done by Milian Wolff

Still some flickering and no marks which parts changed.

The icons are taken from the old designer for now.

Alignment at void*-boundaries for small types.
Read out pointer array directly instead of dereferencing ** for
large types for speed.

Reviewed-by: Alessandro Portale