Merge pull request #37 from a-f-G-U-C/add-zps-port

add ZPS port

portnums.proto

@@ -119,6 +119,13 @@ enum PortNum {
      */
      ENVIRONMENTAL_MEASUREMENT_APP = 67;
 
+    /*
+     * Experimental tools for estimating node position without a GPS
+     * Maintained by Github user a-f-G-U-C (a Meshtastic contributor)
+     * Project files at https://github.com/a-f-G-U-C/Meshtastic-ZPS
+     */
+    ZPS_APP = 68;
+
     /*
      * Private applications should use portnums >= 256.
      * To simplify initial development and testing you can use "PRIVATE_APP"