extract_translations - auxiliary tool that extracts lines to be translated
from ejabberd source tree.
erl -noinput -s extract_translations -extra dirname message_file
where dirname is the directory "src" in ejabberd's source tree root,
message_file is a file with translated messages (src/msgs/*.msg).
Result is a list of messages from source files which aren't contained in
erl -noinput -s extract_translations -extra -unused dirname message_file
Result is a list of messages from message file which aren't in source