Integrate treemap visualisation into lume charts

[gilesdring]

• Sensible default values for all critical parameters
  • In principle it should be possible to create a treemap with one or two parameters
  • Implied hierarchy
  • Sensible mapping to structure
• Examples
  • Minimal config - single hierarchy
  • More complex examples
• Basic documentation
• Testing for difficult people

[gilesdring]

Missing tooltips - @slowe working on generic tooltip.js - will integrate with this when done.

[gilesdring]

Now done.