Enable allowing/disallowing supply to a station, per cargo

Ctrl-click station cargo rating

src/saveload/extended_ver_sl.h

@@ -77,6 +77,7 @@ enum SlXvFeatureIndex {
 	XSLFI_DEBUG,                                  ///< Debugging info
 	XSLFI_FLOW_STAT_FLAGS,                        ///< FlowStat flags
 	XSLFI_SPEED_RESTRICTION,                      ///< Train speed restrictions
+	XSLFI_STATION_GOODS_EXTRA,                    ///< Extra station goods entry statuses
 
 	XSLFI_RIFF_HEADER_60_BIT,                     ///< Size field in RIFF chunk header is 60 bit
 	XSLFI_HEIGHT_8_BIT,                           ///< Map tile height is 8 bit instead of 4 bit, but savegame version may be before this became true in trunk