AMI: Add parking position parameter to Park action

Add a parking space extension parameter (ParkingSpace) to the Park action.
Park action will attempt to park the call to that extension.
If the extension is already in use, then execution will continue at the next priority.

UserNote: New ParkingSpace parameter has been added to AMI action Park.

res/parking/parking_manager.c

@@ -93,6 +93,11 @@
 			<parameter name="Parkinglot" required="false">
 				<para>The parking lot to use when parking the channel</para>
 			</parameter>
+			<parameter name="ParkingSpace" required="false">
+				<para>The parking space extension in the parking lot.
+					If the space is already in use then execution will continue at the next priority.
+				</para>
+			</parameter>
 		</syntax>
 		<description>
 			<para>Park an arbitrary channel with optional arguments for specifying the parking lot used, how long
@@ -523,6 +528,7 @@ static int manager_park(struct mansession *s, const struct message *m)
 	const char *announce_channel = astman_get_header(m, "AnnounceChannel");
 	const char *timeout = astman_get_header(m, "Timeout");
 	const char *parkinglot = astman_get_header(m, "Parkinglot");
+	const char *parkingspace = astman_get_header(m, "ParkingSpace");
 	char buf[BUFSIZ];
 	int timeout_override = -1;
 
@@ -557,7 +563,11 @@ static int manager_park(struct mansession *s, const struct message *m)
 		ast_bridge_set_transfer_variables(chan, timeout_channel, 0);
 		ast_channel_unlock(chan);
 	}
-
+	
+	if (!ast_strlen_zero(parkingspace)) {
+		pbx_builtin_setvar_helper(chan, "PARKINGEXTEN", parkingspace);
+	}
+	
 	parker_chan = ast_channel_bridge_peer(chan);
 	if (!parker_chan || strcmp(ast_channel_name(parker_chan), timeout_channel)) {
 		if (!ast_strlen_zero(announce_channel)) {