Added Zwerkules Rural override tileset

Added Zwerkules Rural override tileset.

_content/biorural/ttr01_b20_01.wok

@@ -0,0 +1,47 @@
+# Rewritten by CleanModels 3 Version 3.5.1 Sun Jul 07 18:55:39 2019
+#MAXWALKMESH  ASCII
+beginwalkmeshgeom ttr01_b20_01
+node aabb walkmesh
+  parent ttr01_b20_01
+  position 0 0 0
+  orientation 0 0 0 0
+  wirecolor 1 1 1
+  bitmap NULL
+  render 0
+  shadow 0
+  verts 9
+    -5 0 -3.4
+    -5 -5 -3.4
+    0 0 -3.4
+    0 -5 -3.4
+    5 0 -3.4
+    5 -5 -3.4
+    -5 5 -3.4
+    0 5 -3.4
+    5 5 -3.4
+  faces 8
+    0 1 2 1 0 0 0 17
+    3 2 1 1 0 0 0 17
+    2 3 4 1 0 0 0 17
+    5 4 3 1 0 0 0 17
+    6 0 7 1 0 0 0 17
+    2 7 0 1 0 0 0 17
+    7 2 8 1 0 0 0 17
+    4 8 2 1 0 0 0 17
+  aabb     -5 -5 -3.4 5 5 -3.4 -1
+    -5 -5 -3.4 0 5 -3.4 -1
+    -5 -5 -3.4 0 0 -3.4 -1
+    -5 -5 -3.4 0 0 -3.4 0
+    -5 -5 -3.4 0 0 -3.4 1
+    -5 0 -3.4 0 5 -3.4 -1
+    -5 0 -3.4 0 5 -3.4 4
+    -5 0 -3.4 0 5 -3.4 5
+    0 -5 -3.4 5 5 -3.4 -1
+    0 -5 -3.4 5 0 -3.4 -1
+    0 -5 -3.4 5 0 -3.4 2
+    0 -5 -3.4 5 0 -3.4 3
+    0 0 -3.4 5 5 -3.4 -1
+    0 0 -3.4 5 5 -3.4 6
+    0 0 -3.4 5 5 -3.4 7
+endnode
+endwalkmeshgeom ttr01_b20_01