Computes feature of a time series based on sliding (overlapping) windows.
`max_level_shift`

finds the largest mean shift between two consecutive windows.
`max_var_shift`

finds the largest var shift between two consecutive windows.
`max_kl_shift`

finds the largest shift in Kulback-Leibler divergence between
two consecutive windows.

## Arguments

- x
a univariate time series

- width
size of sliding window

## Value

A vector of 2 values: the size of the shift, and the time index of the shift.

## Details

Computes the largest level shift and largest variance shift in sliding mean calculations

## Author

Earo Wang and Rob J Hyndman