Added --unmask_dest option to make_remap_weights.py tool

[aidanheerdegen]

Added --unmask_dest option to make_remap_weights.py to allow generation of unmasked remapping files.

This is related to #173 where changes in land mask caused segmentation faults in CICE

This is an example invocation:

./make_remap_weights.py /short/x77/nah599/access-om2/input/ /g/data1/ua8/JRA55-do/RYF/v1-3/ /short/x77/nah599/access-om2/input/yatm_1deg/ --atm JRA55 --ocean MOM1 --npes 4 --unmask_dest

[aidanheerdegen]

I tested with and without the new command line option and it worked as expected.

As this is a relatively simple change in the tools, not any of the models, and does not affect default behaviour I will merge it.