Alternative installation instructions

[ceball]

Not suggesting you merge this yet, but what do you think? I tried to make the instructions simpler. It's a bit opinionated (for instance, I like virtualenv...but not as much as I like anaconda, so I removed most talk about virtualenv).

Also, I think when you install Ubuntu you don't get a C compiler - you have to install build-essential. Am I right?

[ceball]

It would be nice if we could shorten the instructions a lot more, but provide some recipes (specific to particular platforms, and that we test automatically). But I don't think we can do this yet.

Installing

• Get required topographica environment (henceforth referred to as TOPOENV): python 2.7, numpy, pil (and optional matplotlib, scipy, ipython, gmpy). E.g. install anaconda python, or use your system's package manager, or use your existing python environment (possibly with virtualenv).
• install topographica via TOPOENV's pip: pip install topographica

Running

• Activate your TOPOENV (e.g. ensure $TOPOENV/bin is on your path) and run topographica or topographica -g for GUI.
• Examples and models are in TOPOENV's share/topographica folder. E.g.topographica -g $TOPOENV/share/topographica/examples/tiny.ty.

Recipes

...

[ceball]

I meant to say, I could just replace the current Ubuntu recipe with the anaconda one from this PR. That shouldn't be controversial.

(Although it may be that the Ubuntu recipe actually works now - I haven't tested it.)

[jbednar]

I'm too tired to study the details, but the changes look good to me, and so it can be merged once the TODO is deleted. I belive that Ubuntu would always normally have a C compiler, and so I don't think you need to dwell on that much, but mentioning buid_essential as you do now seems fine.