Web Bundle Tutorial: Choose other default options for demo 3 + 4

[thinkh]

• web_bundle version: 0.0.1
• browser version: Firefox 49.0.1
• OS: Windows 10

Reproducer:

Open Demo 3 and Demo 4

Observed behavior:

Expected behavior:

A different default selection from the two drop downs that give a better impression, e.g. as follows:

[mccalluc]

@thinkh: Do you know how to do this? I tried for a bit but didn't figure it out.

[thinkh]

1. Extend the options
2. Replace the default selectedIndex
3. Use the new options in the tutorial

Alternatively (and maybe better), would be to pass the column name and you select the index by this name.

[mccalluc]

I think this is not a rare use case, and configuring it should be easier. I've filed phovea/phovea_vis#5. Closing.