Use modern API and handle smoothing client-side

[bmschmidt]

The client current making a bunch of calls using old methods that require extra work on the API to support that makes it harder to upgrade, particularly calling using the "return_query_values" method and asking the API to handle smoothing.

I'm just doing that myself: I've changed all the calls from the GUI so they're using the modern form [https://github.com/bmschmidt/BookwormGUI/tree/fetchJSON](on this branch).
A demo version is up here.
The only catch is that it may need changes to make sure it works with legacy installations (built before the current version of Presidio); I haven't fully tested that yet, but will do so when I get a chance, and file the appropriate pull request.

Any upgrade will require updating the API at the same time; the new API should still support old GUIs, but there's no reason not to update them all.

So just a flag that that's coming down the pike, for now.