Fixing startup costs and initial conditions

This release includes a new set of initial conditions (and the code to parse them); these now include initial generator outputs (previously set to be Pmin). We also updated the startup costs for thermal generators, which had originally been too high. The startup costs now have a fixed $ / MW of Pmax (cold, warm and hot) startup cost for each group of the generators using the following four types of fuel: 'SUB (Subbituminous Coal)', 'LIG (Lignite Coal)', 'NG (Natural Gas)' and 'PC (Petroleum Coke)'. The $/MW of Pmax costs for each group is set based on its largest unit.