Added an errors test for pixel2map. Fixed a small issue while checking that...

Added an errors test for pixel2map. Fixed a small issue while checking that the bands of multiple files were the same depth. Fixes #4535.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@7292 41f8697f-d340-4b68-9986-7bafba869bb8