Don't use the IP2 value from the file.  Regenerate it from DEET and NPAS.

This is consistent with how the RPN standard library handles the dates.
Merge branch 'fix_forecast'
Propogate the --squash-forecasts option to the RPN_Var initializer.

This will allow us to squash the time/forecast axes early on, so we don't need
to worry about non-applicable conditions like times/forecasts forming a nice
grid.
Version 0.6.0