Rather than producing separate files for each module, the default build now
produces a single file. This should encourage better page-load performance as
the files were relatively small. Also, it's easier to deal with only one file
rather than many, especially if you're not quite sure what the dependencies are.
You may still create minimized builds, if you don't want every feature.
This commit also demotes the chart components to the examples directory, rather
than keeping them as part of the core library. As always, D3 is not a charting
library, and these were ever only intended to serve as examples.
This allows you to specify how the drag behavior should infer the current
position of the targetted element, such that a fixed offset can be maintained
between the mouse position and the element position for the duration of the drag
gesture. For example, if your data is an {x, y} object, use origin(Object).
Mike Bostock
Kristofer Monisit
Jason Davies