Drag n zoom

[simontegg]

Problem: sometimes part of the chart is drawn off-screen.

This pr allows user to drag the graph by holding down the mouse and moving and zoom around a point by using the mousewheel or two finger zoom on the touchpad.

• clicking on an agent no the context brings that agent back to the centre.
• dragging and zooming update the querystring, allowing the user to share particular views.

[ahdinosaur]

this looks really great! :deciduous_tree:

[simontegg]

Ta,

I've noticed a bug: when tags are removed it sometime resets the vector back to a previous position if you'v been dragging it around. Probably related to the mutable vector state split over colaStore and routeStore

[ahdinosaur]

ah hmm okay, happy to merge a bug fix, let me know if you want some :eyes: anywhere.

[ahdinosaur]

deployed :tada: