+ provide access to 'root' collision shape, in case the original collision shape is temporarily replaced by a child collision shape.

+ added MultiMaterialDemo showing how to use the new btTriangleIndexVertexMaterialArray.
Thanks to Alex Silverman for this contribution!

src/BulletCollision/CollisionShapes/btMaterial.h

@@ -0,0 +1,34 @@
+/*
+Bullet Continuous Collision Detection and Physics Library
+Copyright (c) 2003-2008 Erwin Coumans  http://continuousphysics.com/Bullet/
+
+This software is provided 'as-is', without any express or implied warranty.
+In no event will the authors be held liable for any damages arising from the use of this software.
+Permission is granted to anyone to use this software for any purpose, 
+including commercial applications, and to alter it and redistribute it freely, 
+subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
+2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
+3. This notice may not be removed or altered from any source distribution.
+*/
+
+/// This file was created by Alex Silverman
+
+#ifndef MATERIAL_H
+#define MATERIAL_H
+
+// Material class to be used by btMultimaterialTriangleMeshShape to store triangle properties
+class btMaterial
+{
+    // public members so that materials can change due to world events
+public:
+    btScalar m_friction;
+    btScalar m_restitution;
+    int pad[2];
+
+    btMaterial(){}
+    btMaterial(btScalar fric, btScalar rest) { m_friction = fric; m_restitution = rest; }
+};
+
+#endif // MATERIAL_H