chord layout: from matrix input to connections input. Untested, unstable
fixed an awful lot of bugs, but still not working.
produced first graphics
fixed bug on for loop variable. Leftover from original d3 version.
fixed empty spaces and single-band connections
added list of vertices for each polygon, to enable fading of an entire polygon
vertices property of polygons element is now Object for faster lookup
adjusted name to doc notation
minor changes in comments