method described here : https://doi.org/10.1016/j.spasta.2018.10.001
Elsa_categorical_matrix_window(mat, window, dist)
a NumericVector : the local values of ELSA
an IntegerMatrix, must be filled with integer, -1 indicates NA values, categories must start at 0
the window to use to define neighbours. 0 can be used to indicate that a cell is not a neighbour
a distance matrix between the categories