stack method added in addition to concatenate (kind of similar to from_arrays but w/o alignment)
stack_ds and concatenate_ds for similar method to be applied on dataset
read_multinc function, wrapped in read_nc (multiple netCDF files can be read)
added `align` parameter to stack, stack_ds and read_multinc to align datasets/arrays prior to stacking
read_nc now recognizes regular expressions
+ improved documenation