- extended walltype to directly manage Blood's XWALL.

Unfortunately this had to be done in the base class so that we can still maintain the walls in a global array.
The tradeoffs of better abstractions would be far too costly here than the added 16 bytes to the wall struct.

source/core/maploader.cpp

@@ -46,6 +46,7 @@
 #include "render.h"
 #include "hw_sections.h"
 #include "interpolate.h"
+#include "games/blood/src/mapstructs.h"
 
 // needed for skipping over to get the map size first.
 enum
@@ -58,6 +59,16 @@ enum
 	wallsize7 = 32,
 };
 
+// This arena stores the larger allocated game-specific extension data. Since this can be freed in bulk a memory arena is better suited than malloc.
+static FMemArena mapDataArena;
+
+void walltype::allocX()
+{
+	using XWALL = BLD_NS::XWALL;
+	_xw = (XWALL*)mapDataArena.Alloc(sizeof(XWALL));
+	memset(_xw, 0, sizeof(XWALL));
+}
+
 
 static void ReadSectorV7(FileReader& fr, sectortype& sect)
 {