Minor tweaks to some of the objects to make indexing them easier.

engine.py

@@ -43,3 +43,9 @@ class Mesh:
 				row3 = self.vertices[int(tmp[3]) - 1]
 
 				self.triangles.append(Triangle(Matrix3x3(row1, row2, row3)))
+				
+	def __getitem__(self, key):
+		return self.triangles[key]
+		
+	def __len__(self):
+		return len(self.triangles)