Allow articulated road vehicles to overtake other vehicles

Add setting

src/saveload/extended_ver_sl.cpp

@@ -103,6 +103,7 @@ const SlxiSubChunkInfo _sl_xv_sub_chunk_infos[] = {
 	{ XSLFI_DUAL_RAIL_TYPES,        XSCF_NULL,                1,   1, "dual_rail_types",           nullptr, nullptr, nullptr        },
 	{ XSLFI_CONSIST_SPEED_RD_FLAG,  XSCF_NULL,                1,   1, "consist_speed_rd_flag",     nullptr, nullptr, nullptr        },
 	{ XSLFI_SAVEGAME_UNIQUE_ID,     XSCF_IGNORABLE_ALL,       1,   1, "savegame_unique_id",        nullptr, nullptr, nullptr        },
+	{ XSLFI_RV_OVERTAKING,          XSCF_NULL,                1,   1, "roadveh_overtaking",        nullptr, nullptr, nullptr        },
 	{ XSLFI_NULL, XSCF_NULL, 0, 0, nullptr, nullptr, nullptr, nullptr },// This is the end marker
 };
 

src/saveload/extended_ver_sl.h

@@ -70,6 +70,7 @@ enum SlXvFeatureIndex {
 	XSLFI_DUAL_RAIL_TYPES,                        ///< Two rail-types per tile
 	XSLFI_CONSIST_SPEED_RD_FLAG,                  ///< Consist speed reduction flag
 	XSLFI_SAVEGAME_UNIQUE_ID,                     ///< Savegame unique ID
+	XSLFI_RV_OVERTAKING,                          ///< Roadvehicle overtaking
 
 	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