Get game's current world save folder

Use World::ReadWorldFolder() to get "region1" (or whatever it currently
is).  Only have offset for Linux.

Memory.xml

@@ -1028,6 +1028,7 @@
                 <Address name="current_weather" description="5x5 array of bytes for surrounding biomes. For each: 0=clear, 1=raining, 2=snowing." />
                 <Address name="game_mode" description="Current game mode" />
                 <Address name="control_mode" description="Current control mode" />
+                <Address name="save_folder" descript="Name of save folder of current game"/>
                 <!--<Address name="control_mode_copy" description="Copy of the control mode in DF memory" />-->
             </Group>
             <Group name="Legends">
@@ -3058,6 +3059,7 @@
                 <Address name="control_mode" value="0x8c3de90" />
                 <Address name="game_mode" value="0x8c3deA0" />
                 <Address name="current_weather" value="0x93F05E4" />
+                <Address name="save_folder" value="0x958a378" />
             </Group>
             <Group name="Items">
                 <Address name="items_vector" value="0x940b1fc" />

library/include/dfhack/modules/World.h

@@ -107,6 +107,7 @@ namespace DFHack
         void SetCurrentWeather(uint8_t weather);
         bool ReadGameMode(t_gamemodes& rd);
         bool WriteGameMode(const t_gamemodes & wr); // this is very dangerous
+        std::string ReadWorldFolder();
         private:
         struct Private;
         Private *d;

library/modules/World.cpp

@@ -67,6 +67,10 @@ struct World::Private
     uint32_t gamemode_offset;
     uint32_t controlmode_offset;
     uint32_t controlmodecopy_offset;
+
+    bool StartedFolder;
+    uint32_t folder_name_offset;
+
     Process * owner;
 };
 
@@ -106,6 +110,14 @@ World::World()
         d->StartedMode = true;
     }
     catch(Error::All &){};
+    try
+    {
+        d->folder_name_offset = OG_World->getAddress( "save_folder" );
+        d->StartedFolder = true;
+    }
+    catch(Error::All &){};
+
+
     d->Inited = true;
 }
 
@@ -220,3 +232,12 @@ void World::SetCurrentWeather(uint8_t weather)
         d->owner->write(d->weather_offset,sizeof(buf),buf);
     }
 }
+
+string World::ReadWorldFolder()
+{
+    if (d->Inited && d->StartedFolder)
+    {
+        return string( * ( (string*) d->folder_name_offset ) );
+    }
+    return string("");
+}