In maptrim, changed the temporary file name to be unique between executions so...

In maptrim, changed the temporary file name to be unique between executions so there are no conflicts when multiple instances of the program are running. Added an app test to exercise this change. Fixes #1216.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@4964 41f8697f-d340-4b68-9986-7bafba869bb8