yt development: Documentation

As a result of progress in my scientific goals, and the application of recent yt developments to them, I did not make many changes or developments in yt this week. When I did work on yt, I primarily spent time re-organizing the documentation and fixing several errors. I have added an "installation" section, consolidated a few sections, and wrote two new sections on how to make plots and on how to generate derived data products. I think that the documentation is now much easier to navigate and follow.

This week I also fine-tuned the API for the bridge that connects Enzo and Python, relying on feedback from other Enzo developments. This work is the first step in creating a generalized library for constructing initial conditions; it is not meant to be Enzo-specific. I will report more on this, but the ultimate goal is to be able to construct initial conditions using scripts, rather than constructing multiple C routines. This should make scientific experimentation much more accessible.

One final note is that this last week saw the first successful execution of a large-scale Enzo simulation with inline analysis provided by yt, using the `EnzoStaticOutputInMemory` object. BrittonS is driving that simulation forward, and he's also conducting benchmarks to see how expensive inline analysis is.