Fix bug and errors related to date_range

1. Error of date range calculation in run_snow_annual_map.py : this caused the failed test

date_range = date_stop - date_start +1

this correction alone makes the test pass OK.. but the baseline was wrong (see 3.)

2. Bug in compute_smod_sod.py

the default input date_range param was given as int (365) but its is used as a timedelta object

it should be : date_range = (date_stop - date_start).days +1

3. Last band was not read by rasterio in compute_*.py because python's range excludes the stop values: it should be

W = src.read(range(1, date_range+1))