diag_ts: Time Series Diagnostics
In SMAC-Group/exts: Experimental Features for Time Series

Provides a list structure containing time series diagnostic information

1	diag_ts(model, xt, std = TRUE, test = "ljung-box", robust = FALSE)

`model`	An `arima` object.
`xt`	The data used to construct said model.
`std`	A `boolean` indicating whether residuals should be standardized.
`test`	A `string` indicating the type of portmanteau test to run.
`robust`	A `boolean` indicating whether the ACF should be robust (`TRUE`) or not (`FALSE`).