AP_Parachute: add example sketch

Only tests that the lib compiles

libraries/AP_Parachute/examples/AP_Parachute_test/AP_Parachute_test.pde

+/*
+ *       Example of AP_Parachute library.
+ *       DIYDrones.com
+ */
+
+#include <AP_Common.h>
+#include <AP_Progmem.h>
+#include <AP_Math.h>            // ArduPilot Mega Vector/Matrix math Library
+#include <AP_Param.h>
+#include <AP_HAL.h>
+#include <AP_HAL_AVR.h>
+#include <RC_Channel.h>
+#include <AP_Relay.h>
+#include <AP_Parachute.h>
+
+const AP_HAL::HAL& hal = AP_HAL_BOARD_DRIVER;
+
+// Relay
+AP_Relay relay;
+
+// Parachute
+AP_Parachute parachute(relay);
+
+void setup()
+{
+    hal.console->println("AP_Parachute library test");
+}
+
+void loop()
+{
+    // print message to user
+    hal.console->printf_P(PSTR("this example tests compilation only"));
+    hal.scheduler->delay(5000);
+}
+
+AP_HAL_MAIN();