Finish cltcart implementation
Add a menu

Allow the different cartograms to be animated between interactively.
Colour by continent

Colour in the map, to make it look nicer.
Scale up the map

Make it bigger.
Makefile rule for cltcart
Add a blurred map for comparison

Create a cartogram with blur radius = 2 using the DCT algorithm,
as another example of a speed/accuracy tradeoff, for comparison.