Add --rotate-poly option to transfer_to_mosaic.c

[dougiesquire]

Description
This PR adds the --rotate_poly option to transfer_to_mosaic.c.

Fixes #362

How Has This Been Tested?
I've converted old format grids to mosaic format using the added option. Areas at/near the pole are more sensible than without --rotate_poly.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules
• New check tests, if applicable, are included
• make distcheck passes