move text message handling into the new general plugin system

mesh.proto

@@ -162,9 +162,13 @@ message SubPacket {
   // Only one of the following fields can be populated at a time
   oneof payload {
 
-    Position position = 1;
+    /// Prior to 1.20 positions were communicated as a special payload type, now they are GPS_POSITION_APP Data
+    Position position = 1 [deprecated = true];
+
     Data data = 3;
-    User user = 4;
+
+    /// Prior to 1.20 positions were communicated as a special payload type, now they are MESH_USERINFO_APP
+    User user = 4 [deprecated = true];
 
     /**
     A route request going from the requester

portnums.proto

@@ -38,4 +38,14 @@ enum PortNum {
     // Note: this concept has been removed for now.  Once READACK is implemented, use the 
     // new packet type/port number stuff?
     // CLEAR_READACK = 2;
+
+    // Future standard app IDs
+    GPIO_APP = 2;
+    GPS_POSITION_APP = 3;
+    MESH_USERINFO_APP = 4;
+    IP_TUNNEL_APP = 5;
+
+    /// Private applications should use portnums >= 256.  To simplify initial development and testing you can use "PRIVATE_APP"
+    /// in your code without needing to rebuild protobuf files (via bin/regin_protos.sh)
+    PRIVATE_APP = 256;
   }