Changed Doxygen configuration to output warnings to logfile, warnings always...

Changed Doxygen configuration to output warnings to logfile, warnings always generated, MODE=LOUD no longer effects warning generation. m04585

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@7494 41f8697f-d340-4b68-9986-7bafba869bb8