Modify uORB API to allow cleaner in-app use

src/modules/uORB/uORB.h

@@ -181,6 +181,29 @@ extern orb_advert_t orb_advertise(const struct orb_metadata *meta, const void *d
 extern orb_advert_t orb_advertise_multi(const struct orb_metadata *meta, const void *data, int *instance,
 					int priority) __EXPORT;
 
+/**
+ * Advertise and publish as the publisher of a topic.
+ *
+ * This performs the initial advertisement of a topic; it creates the topic
+ * node in /obj if required and publishes the initial data.
+ *
+ * Any number of advertisers may publish to a topic; publications are atomic
+ * but co-ordination between publishers is not provided by the ORB.
+ *
+ * @param meta		The uORB metadata (usually from the ORB_ID() macro)
+ *			for the topic.
+ * @param data		A pointer to the initial data to be published.
+ *			For topics updated by interrupt handlers, the advertisement
+ *			must be performed from non-interrupt context.
+ * @param instance	Pointer to an integer which will yield the instance ID (0-based,
+ *			limited by ORB_MULTI_MAX_INSTANCES) of the publication.
+ * @param priority	The priority of the instance. If a subscriber subscribes multiple
+ *			instances, the priority allows the subscriber to prioritize the best
+ *			data source as long as its available.
+ * @return	zero on success, error number on failure
+ */
+extern int orb_publish_auto(const struct orb_metadata *meta, orb_advert_t *handle, const void *data, int *instance,
+			    int priority)
 
 /**
  * Publish new data to a topic.