Resolve "Does multiprocessing in sen2chain work within "Python Virtual Env" ?"

Closes #20

See merge request espace-dev/sen2chain!21

introduction of new geo_utils.full_db_2_shp function to extract tile dbase to shapefile with number, first and last date of each product: l1c, l2a and all indices, 40x faster than old get_processed_indices_vect function that will be deprecated

in Library l1c, l2a and all indices now return tiles names with at least one product (empty folder removed)