Introduced btActionInterface. This makes it easier to extend user-defined actions, such as vehicles and characters.

btRaycastVehicle and btKinematicCharacterController are derived from btActionInterface now.
Some cosmetic cleanup: changed sourceforce/sf.net url to bulletphysics.com.

Demos/HeightFieldFluidDemo/BulletHfFluid/btHfFluid.h

@@ -1,3 +1,20 @@
+/*
+Bullet Continuous Collision Detection and Physics Library
+Copyright (c) 2003-2009 Erwin Coumans  http://bulletphysics.com
+
+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.
+
+Experimental Buoyancy fluid demo written by John McCutchan
+*/
+
 #ifndef __HFFLUID_H
 #define __HFFLUID_H
 
@@ -14,6 +31,7 @@ class btManifoldResult;
 // add buoyant convex vs. convex / concave
 // add buoyant concave support (try bunny model)
 
+///experimental buyancy fluid demo
 class btHfFluid : public btCollisionObject
 {
 public: