JPSSnagg

Completed the implementation of -l option.  It knows how to handle various
settings of -g options too.

src/nagg_options.c:
    Added code to handle different settings of -g option that affect -l/-t
    option.
    Removed -V option.  Changed --version to print versions and continued.
    
src/nagg_select_granules.c:
    updated two assert conditions to handle the case that products_list
    can be a NULL when nproducts is not >0.

test/testnagg.sh
    Added two more -l tests.

Tested: koala and Jam using gcc.