Persistence forecasts for coal and gas prices

[mfripp]

I just switched the repository over to using the last 5 years of state-level coal and gas prices as the forecast for future years. There are more details on that (and how to switch back to AEO or NYMEX forecasts) in the commit log. You should be able to get these changes just by running git pull and then running pg_to_switch.py the usual way.

Also, sorry to say, but despite my promise of active discussion here, I'll be out of office Nov. 24-28, so may not get back to these discussions and requests until early December. But I haven't forgotten!