This is useful when stopping the layout in response to a user action, e.g. if another layout is used to position the nodes in an event handler. In this case, we don't want the next tick of the force layout to run as it could undo the positioning work done in the event handler.
This is ported from the Protovis implementation, pv.Layout.Rollup. The only difference is that the rollup nodes are not instances of any original nodes (Protovis used pv.extend). Users are expected to use the "x" and "y" properties of the rollup node, or alternatively the "rolled up" nodes can be retrieved via the "nodes" property.
…mal part. included additional tests to demonstrate fixes.
…led the old method.
…year-time-scale' and 'dispatch-chain' into release
Fixes #428. This is built on top of existing tick support for linear scales: for small intervals, a linear scale computes ticks based on milliseconds; for large intervals, a linear scale computes ticks based on fractional years. This commit also extends the time scale's formatter to display milliseconds.