GPS: add GPS_UBLOX_passthrough sketch

This sketch allows the user to configure the Ublox GPS using U-Center
without the need for an FTDI cable.

libraries/AP_GPS/examples/GPS_UBLOX_passthrough/GPS_UBLOX_passthrough.pde

@@ -0,0 +1,44 @@
+// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+/*
+ *       GPS UBlox passthrough sketch
+ *       Code by DIYDrones.com
+ *
+ *       Works with APM2.x
+ */
+
+#include <stdlib.h>
+#include <AP_Common.h>
+#include <AP_Progmem.h>
+#include <AP_Param.h>
+#include <AP_HAL.h>
+#include <AP_HAL_AVR.h>
+#include <AP_HAL_Empty.h>
+#include <AP_HAL_PX4.h>
+#include <AP_GPS.h>
+#include <AP_Math.h>
+#include <AP_Notify.h>
+
+const AP_HAL::HAL& hal = AP_HAL_BOARD_DRIVER;
+
+void setup()
+{
+    // initialise console uart to 38400 baud
+    hal.console->begin(38400);
+
+    // initialise gps uart to 38400 baud
+    hal.uartB->begin(38400);
+}
+
+void loop()
+{
+    // send characters received from the console to the GPS
+    while (hal.console->available()) {
+        hal.uartB->write(hal.console->read());
+    }
+    // send GPS characters to the console
+    while (hal.uartB->available()) {
+        hal.console->write(hal.uartB->read());
+    }
+}
+
+AP_HAL_MAIN();

libraries/AP_GPS/examples/GPS_UBLOX_passthrough/Makefile

@@ -0,0 +1,2 @@
+BOARD	=	mega
+include ../../../../mk/apm.mk