Add tags to selection box

[Garbash]

In addition to current behaviour, Shift-click on node results in the selection appearing as a tag in in selection box #463

Each tag will have a little "x" in the top right corner that if clickec:

• Removes the tag from the selection box
• Deselects the node

A possible library for tags: https://select2.github.io/examples.html

[Garbash]

3closed as this issue was broken down into #470 #469 #468 #467 #466

[Garbash]

Reopened because tags UI for selection is helpful