- handle dsda namespace like zdoom in udmf

src/maploader/udmf.cpp

@@ -2477,6 +2477,7 @@ public:
 			namespc = sc.String;
 			switch(namespc.GetIndex())
 			{
+			case NAME_Dsda:
 			case NAME_ZDoom:
 			case NAME_Eternity:
 				namespace_bits = Zd;

src/namedef_custom.h

@@ -675,6 +675,7 @@ xx(ZDoomTranslated)
 xx(Vavoom)
 xx(GZDoom)
 xx(Eternity)
+xx(Dsda)
 
 xx(Xpanningfloor)
 xx(Ypanningfloor)