Improve css for the drill down
Add a color legend
Add possibility off drill down and roll up on regions
Integration test of the map
Update test file
Rename a function with rigth name
Increase the minimum delay between 2 drill-down

During tests, it happend very often that a mouse scroll launched 2 drill down. This is due to the fact that the browser is busy and delay part of the multiples mouse scrolls (because we never scroll by one unit), probably because of the render of the SVG, and finally a scroll manage to pass the 700ms previous limit. With 3s, it's much better and none should drill down twice in 3s.
Add possibility to set the number of zoom levels

By default, the number of zoom levels is 0 and mouse scroll won't do anything.
And you can set the number of zoom levels with setNbZoomLevels to enable the possibility to zoom with mouse wheel up to the defined number of levels.
Smarten the doRedraw function

The doRedraw function now add the missing layers and delete the useless ones.
It is way quicker than calling doRender.
Merge pull request #4 from loganalysis/feature-geo-choropleth-chart

Feature geo choropleth chart