Fixing the Texas-7k Grid

This is the first production release that uses a fixed version of the Texas-7k grid; these fixes are documented in the pre-releases for this version. In total, these fixes have produced a grid with much more reasonable load shedding amounts, as well as far fewer instances of extreme bus LMPs.

Other updates include better documentation and more features exposed in the command line interface, including the ability to save and load initial conditions.