Add image for zandronum

zandronum needs a set of packages that are outdated.

games/zandronum/entrypoint.sh

@@ -0,0 +1,13 @@
+#!/bin/bash
+cd /home/container
+
+# Make internal Docker IP address available to processes.
+INTERNAL_IP=$(ip route get 1 | awk '{print $(NF-2);exit}')
+export INTERNAL_IP
+
+# Replace Startup Variables
+MODIFIED_STARTUP=$(echo -e $(echo -e ${STARTUP} | sed -e 's/{{/${/g' -e 's/}}/}/g'))
+echo -e ":/home/container$ ${MODIFIED_STARTUP}"
+
+# Run the Server
+eval ${MODIFIED_STARTUP}