Use longer variable names within solver

[sdboyer]

trafficstars

I really went overboard on the whole short variable names thing within the solver. The algorithm is hard enough to follow, even for me, when variable names aren't descriptive. This issue is more or less a TODO to go through and change var names in a way that will make working in the solving algorithm less daunting.

[fabulous-gopher]

This issue was moved to golang/dep#412