D3 Nest function - converting csv data to nested data for treemaps etc.

Just finished 8 examples of how to use the javascript visualisation library D3 nest function - notes to self really, but shared in case they are useful for others.

 http://bl.ocks.org/3176159 to see the code
 http://bl.ocks.org/d/3176159/ to see all the examples run.