[FIX](Root Sign) Added a single scene data array to the root mark; when hoverable was false, there was no scene defined on the root panel's sign - this was the only case in which a sign was rendering without a scene; this fact was causing the _inContext method to run with an undefined scene argument, which ended up causing the property '_renderId' being set in the JS  global object.
[FIX](protovis data prop delegation) Like all other protovis properties, the data property now also supports delegation.