CRAN v0.3.1

Small release to resolve check issues with the development and patched versions
of R. The release includes some minor improvements to the output consistency of
initial states in ETS() models, the passing of arguments in ARIMA() models,
and handling of missing values in NNETAR().

Improvements

• Display of ETS initial states now use a state[t] notation to describe the
  state's position in time (#329, #261).
• Allowed specifying method argument in ARIMA() (#330).
• Improved handling of missing values in NNETAR() (#327).

Bug fixes

• Fixed error with forecasting and simulating from NNETAR() estimated using
  a short series (#326).
• Fixed AR() fitted values not being re-scaled to match original data (#318).