[nim] Changed background color of visualisation div to a grey that stands out more
[nim] Visualisation placeholder div sent to back. Will use as visualisation data div
[nim] Now all elements contained within a visualisation div have the same id as the vis div. This will go a long way in translating actions on an element to actions on the relevant visualisation given that we have many visualisations
[nim] Add Visualisation action now exposes controls that only show up when looking at a visualisation