Disclaimer - this works for me, but YMMV. Back up your data before trying this.

for file in `find . -name "*.lua"`
do
   sed -i "s/$1/$2/g" $file
done

for file in `find . -name "*.s3o"`
do
        sed -i "s/$1/$2/g" $file
done


for infile in `find . \( ! -regex '.*/\..*' \)`
do
   newname=`echo $infile | sed "s/$1/$2/"`
   if [ "$infile" != "$newname" ]
   then
      mv $infile $newname
      #### ^^^ important! ^^^
      #if you use a version-control system like SVN or Git,
      # change that line to from "mv" to "git mv",
      # "svn mv", or whatever your VCS requires.
      ####
   fi
done

 ./renameUnit.sh oldunitname newunitname