Add script for finding unused messages

Taken from QA_3_3 and slightly modified. This just checks
libraries/messages.inc.php and could be removed once this file is gone.

scripts/find_unused_messages.sh

@@ -0,0 +1,35 @@
+#!/bin/sh
+
+export LANG=C
+set -e
+
+# Simple script to find unused message strings by Michal Čihař
+
+tmp1=`mktemp`
+tmp2=`mktemp`
+grep -o '^\$\<str[A-Z][a-zA-Z0-9_]*\>' libraries/messages.inc.php \
+    | tr -d '$' \
+    | grep -Ev '^str(Transformation_|ShowStatus)' | sort -u > $tmp1
+grep -ho '\<str[A-Z][a-zA-Z0-9_]*\>' `find . -type f -a -name '*.php' -a -not -path '*/lang/*'` \
+    | grep -Ev '^str(Transformation_|ShowStatus|Setup)' | sort -u > $tmp2
+
+echo Please note that you need to check results of this script, it doesn\'t
+echo understand PHP, it only tries to find what looks like message name.
+
+echo
+echo Used messages not present in messages file:
+echo '(this contains generated messages and composed message names, so these'
+echo 'are not necessary a errors!)'
+echo
+
+# filter out known false positives
+diff $tmp1 $tmp2 | awk '/^>/ {print $2}' | grep -Ev '(strEncto|strXkana|strDBLink|strPrivDesc|strPrivDescProcess|strTableListOptions|strMissingParameter|strAttribute|strDoSelectAll)'
+
+echo
+echo Not used messages present in messages file:
+echo
+
+diff $tmp1 $tmp2 | awk '/^</ {print $2}' | grep -Ev '(strSetup.*_(desc|name)|strSetupForm_|strSetupFormset_)'
+
+
+rm -f $tmp1 $tmp2