libcommon: Kludge around a compatibility issue with Hexen's MAPINFO

MAPINFO in the commercial versions of the Hexen IWADs contain a bunch
of broken definitions. As later definitions now replace earlier ones
(a change from ZDoom), these broken defs will now override the earlier
"good" defs.

For now we'll kludge around this issue by patching such defs with the
original/expected values.

Todo: Determine how ZDoom behaves and replicate that behavior.
Todo for later: Isolate this compatibility swamp by moving the MAPINFO
parser to load time translator plugin.

doomsday/plugins/common/src/p_start.cpp

@@ -252,10 +252,21 @@ static void readMapInfoDefinitions()
     // Read the primary MAPINFO (from the IWAD).
     AutoStr *sourceFile = sc_FileScripts? Str_Appendf(AutoStr_New(), "%sMAPINFO.txt", sc_ScriptsDir)
                                         : AutoStr_FromText("Lumps:MAPINFO");
-    AutoStr *buffer = M_ReadFileIntoString(sourceFile, 0);
+    dd_bool sourceIsCustom;
+    AutoStr *buffer = M_ReadFileIntoString(sourceFile, &sourceIsCustom);
     if(buffer && !Str_IsEmpty(buffer))
     {
         readOneMapInfoDefinition(parser, *buffer, Str_Text(sourceFile));
+
+        // MAPINFO in the Hexen IWAD contains a bunch of broken definitions.
+        // As later map definitions now replace earlier ones, these broken defs
+        // override the earlier "good" defs. For now we'll kludge around this
+        // issue by patching the effected defs with the expected values.
+        if(!sourceIsCustom && (gameModeBits & (GM_HEXEN|GM_HEXEN_V10)))
+        {
+            MapInfo *info = hexDefs.getMapInfo(de::Uri("Maps:MAP07", RC_NULL));
+            info->set("warpTrans", "@wt:6");
+        }
     }
     else
     {
@@ -386,9 +397,9 @@ static void readMapInfoDefinitions()
     for(HexDefs::MapInfos::const_iterator i = hexDefs.mapInfos.begin(); i != hexDefs.mapInfos.end(); ++i)
     {
         MapInfo const &info = i->second;
-        LOG_RES_MSG("MAPINFO %s { title: \"%s\" hub: %i map: %s warp: %i }")
+        LOG_RES_MSG("MAPINFO %s { title: \"%s\" hub: %i map: %s warp: %i nextMap: %s }")
                 << i->first.c_str() << info.gets("title")
-                << info.geti("hub") << info.gets("map") << info.geti("warpTrans");
+                << info.geti("hub") << info.gets("map") << info.geti("warpTrans") << info.gets("nextMap");
     }
 #endif
 }