Finished updating photomet to allow users to trim images based on...

Finished updating photomet to allow users to trim images based on dem/ellipsoid and calculate photometric angles based on dem/ellipsoid. The trimming and calculating are separate, requiring the use of the usedem parameter. Fixes #4180.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@7212 41f8697f-d340-4b68-9986-7bafba869bb8