Mesh Generation GDSCript

This concludes the mesh generation of walls. We can now put holes into
walls deterministically.

demo/scripts/util.gd

@@ -0,0 +1,16 @@
+extends Object
+
+class_name UTIL
+
+# chunks array into 'chunk_size' pieces
+static func chunk_array(arr: Array, chunk_size: int) -> Array:
+	var result_chunks = []
+	var i = 0
+	while i < arr.size():
+		var chunk = arr.slice(i, i + chunk_size)
+		result_chunks.append(chunk)
+		i += chunk_size
+	return result_chunks
+
+static func vector2_to_vector3(v: Vector2) -> Vector3:
+	return Vector3(v.x, v.y, 0)