[wdmmg-dev] New version of the explorer using bubbletree

[Rufus Pollock]

Hi All,

I've extracted the dataset explorer into a pure js app:

<http://demos.openspending.org/openspendingjs/app/explorer-v2/>

You'll need to select something from the drop-down (e.g. cofog1) and
hit redraw to see anything (and wait for a long time).

Next steps:

1. Reintegrate this back into openspending.org/dataset/explorer
2. Allow for provision of default drilldown options
3. Have year slider

Some thoughts on the bubbletree code (@Gregor primarily):

* Bubble tree should just take a standard tree struture
* All code to get that tree (whether off-disk, from openspending API)
should be separate (and outside of bubbletree)

Hence:

* Have a single option to bubble tree: data (or similar)
* Get rid of all other data options (if we really want we can keep
some helper stuff in Loader but let's make simple data provision
primary).
* Move getTree functionality into ./lib/aggregate.js (or similar)
* Refactor examples

Regards,

Rufus