Filter smry/smry_meta in ReservoirSimulationTimeSeriesRegional at initialization

[asnyv]

Can add something like this at the end of __init__() to marginally reduce time to filter later on.

self.smry=self.smry[["ENSEMBLE", "DATE", "REAL"]+self.smry_cols]
self.smry_meta=self.smry_meta[["ENSEMBLE", "DATE", "REAL"]+self.smry_cols]