Add: create bundles via CPack

CPack works closely together with CMake to do the right thing in
terms of bundling (called 'package'). This generates all the
packaging we need, and some more.

os/macosx/launch.sh

@@ -0,0 +1,8 @@
+#!/bin/sh
+
+ROOT_DIR=$(dirname "$0")/..
+
+export DYLD_LIBRARY_PATH=${ROOT_DIR}/Frameworks
+
+cd ${ROOT_DIR}/Resources
+exec ./openttd "$@"