Implement slots in store/data for storing mulitple datasets at once (tags yet to be refactored).

Remove deprecated comp.: Node, Link, LinkedNodesPair (these were copy-pasted versions and dependant on previous store/data implementation). Update accordingly NodeDetailContent.
Move node/link details-on-demand from right tool panes into popovers in graph -> remove unused components: NodePopover, NodeDetail/Link/SelectionPane