This routine is called during the Save wizard, for any key that being
saved, regardless of whether or not it has actually changed. This
is enabled by including the ONSAVE key in the Spec. (In this case it is
automatically enabled by the Pluggable/LANGUAGES.pm
This will remove the languages.cache file from the WorkingDir, so that
the cache can be regenerated.
If compression is enabled, it also compresses the language file.