`VarGetter.GetSlice` is useful only for 1 dimensional data

If a variable has data of multiple dimension, GetSlice will retrieve all the data of the slice of the first dimension.

Example : variable of dimensions `time`, `latitude`, `longitude`

`GetSlice(0, 2)` will retrieve the data for all `latitude`, `longitude`, for the `time` 0 and 1.

I am wondering how this API could be improved to allow slicing all dimensions.