Add "Grouping" demo
Merge 'upstream' into gh-pages-dev
Tweaks for reviews

Applies the "Colour fudge" for column series colours.
Moves the new page up to where "Custom Groupings" was, and renames the
following page to be "grouped" data.
Merge pull request #130 from tpkelly/gh-pages-dev

Add "Grouping" demo