Bring in the enhancements I submitted to mharo some time ago and bump
the version to 2.3.2.

• Add checks for empty files, empty directories, core files, more

possible backup files, dotfiles, symlinks and CVS directories.

• Do not assume PATCHDIR always includes "/files/". Use the best

method to check whether a file is added to @checker as a patch file.

• Some trivial message style fixes.