Improve visualisation graph's UI

[csarven]

View:

• [ ] Add node labels, eg. use getResourceLabel
• [ ] Add node colours, eg. based on rdf:type?
• [ ] Add edge labels
• [ ] Add direction arrows for edges

Filtering:

• [ ] Show/hide node and edge labels
• [ ] Add controls to modify, show/hide certain properties and classes, e.g., data source (graph URIs), creator, license, datestamps.
• [ ] Show only specific data models (derived from rdf:type classes or other properties?), e.g., citations, annotations, policy

Editing:

• [ ] Add statements
• [ ] Link nodes

Interaction:

• [x] On node click of a remote URL, dereference it, and then add into the graph