Change all the functions that use `calc_grid_winds2`, now that it returns a list

[geanders]

Previously, this function returned a matrix with just the sustained wind. Now, it returns a list where that matrix is the first element (i.e., what was grid_winds will now be stored in grid_winds[[1]], aka grid_winds[["vmax_sust"]].

We need to change all the functions that use calc_grid_winds2 so that they extract this element from the list.