predict and forecast MARSS MLE objects

See the following help files:

• predict.marssMLE() Predict and forecast.

• forecast.marssMLE() Forecast. Use predict.marssMLE() to call with argument h.

• plot.marssPredict() Plot a prediction or forecast.

• autoplot.marssPredict() Plot a prediction or forecast using ggplot2 package.

• print.marssPredict() Print prediction or forecast. If h!=0, i.e. forecast, only the forecast is printed but the marssPredict object (in pred) has all the historical time steps also.