Fixed a bug in which Camera would use the wrong subpixel location when...

Fixed a bug in which Camera would use the wrong subpixel location when computing the local normal. Checked in for Victor Silva. Fixes #4560.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@7303 41f8697f-d340-4b68-9986-7bafba869bb8