make launcher suitable for mac environment

readlink -f doesn't work on mac, so i used code salvaged from the internets to simulate the functionality on mac

cataclysm-launcher

@@ -1,11 +1,30 @@
 #!/bin/sh
-DIR=$(dirname "$(readlink -f "$0")")
-BIN=$(basename "$0")
+TARGET_FILE=$0
+
+cd `dirname $TARGET_FILE`
+TARGET_FILE=`basename $TARGET_FILE`
+
+# Iterate down a (possible) chain of symlinks
+while [ -L "$TARGET_FILE" ]
+do
+    TARGET_FILE=`readlink $TARGET_FILE`
+    cd `dirname $TARGET_FILE`
+    TARGET_FILE=`basename $TARGET_FILE`
+done
+
+# Compute the canonicalized name by finding the physical path 
+# for the directory we're in and appending the target file.
+PHYS_DIR=`pwd -P`
+RESULT=$PHYS_DIR/$TARGET_FILE
+echo $RESULT
+
+DIR=$(dirname $RESULT)
+BIN=$(basename $RESULT)
 
 cd "$DIR" || exit $?
 
 # If name does not match a binary or is this same script, find the right one
-if [ ! -f "$BIN" ] || [ "$BIN" = "$(basename "$(readlink -f "$0")")" ]
+if [ ! -f "$BIN" ] || [ "$BIN" = "$(basename $RESULT)" ]
 then
     BIN=
     for bin in cataclysm-tiles cataclysm