Generalise .po file updates

This should catch all future translations too

pyfpdb/locale/update-po-files.sh

@@ -1,3 +1,12 @@
-msgmerge --update fpdb-hu_HU.po fpdb-en_GB.po
-msgmerge --update fpdb-de_DE.po fpdb-en_GB.po
+#!/bin/sh
+
+# Our master file
+REFERENCE_PO=fpdb-en_GB.po
+
+# Update all .po files
+for po in *.po; do
+    if [ ${po} != ${REFERENCE_PO} ]; then
+        msgmerge --update ${po} ${REFERENCE_PO}
+    fi
+done