[Yt-dev] Generic data loader

[Matthew Turk]

Hi all,

In support of the Paraview pipeline between yt/pv, I wrote up a new
frontend called "stream."  Right now it's not unitful, but it is
designed to be lightweight and to accept and transport arbitrary data
around as fully-functional yt hierarchy.  This could be a mechanism
for prototyping new data loaders (or refactoring existing ones,
frankly).  There are likely still bugs in it, but a proof-of-concept
is here:

http://matthewturk.bitbucket.org/html/ba3fd37b-842c-4641-b21e-2d3f5268eefe-stream_proxy-py.html

To be able to project, you need to set the units with spf.units["cm"]
= spf.units["unitary"] = 1.0, because I'm not yet sure how to handle
that exactly.  All this requires is a few parameters, the mesh, and a
manner for generating or loading data.  One could even imagine using
this to construct arbitrary data sets in memory -- for instance, the
field loader could return an analytic value for Density that matches
something.  In my view, this should ultimately be able to handle
conversion to other data formats, and thus the generation of initial
conditions or restart outputs.

Anyway, comments welcome!

-Matt