Add property list callbacks

- Add property list callbacks to sources/outputs/encoders so that if
  necessary user interface can be automatically generated or perhaps a
  property list widget can be used for them.

- Change some of the property API names.  obs_property_list_t felt a bit
  awkward when actually using it, so I just renamed it to
  obs_properties_t.

- Removed the getdata/setdata nad getparam/setparam functions from
  sources/services, they will be superseded by the dynamic procedure
  call API.

libobs/obs-service.h

@@ -26,10 +26,7 @@ struct service_info {
 
 	void *(*create)(obs_data_t settings, struct service_data *service);
 	void (*destroy)(void *data);
-	void (*config)(void *data, obs_data_t settings);
-
-	/* optional */
-	const char *(*getdata)(const char *attribute);
+	void (*update)(void *data, obs_data_t settings);
 
 	/* get stream url/key */
 	/* get (viewers/etc) */