Remove dead code from features.c; refactor pickup code into pickup.c

This patch does the following:
 * It moves the pickup code out of features.c and into pickup.c
 * It removes the vast majority of dead code out of features.c. In particular,
   this includes the parking code.

(issue ASTERISK-22134)



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@396060 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_parking.c

@@ -1227,6 +1227,9 @@ static int reload_module(void)
 
 static int unload_module(void)
 {
+
+	/*ast_parking_unregister_bridge_features(parking_provider.module_name);*/
+
 	/* XXX Parking is currently not unloadable due to the fact that it loads features which could cause
 	 *     significant problems if they disappeared while a channel still had access to them.
 	 */