Move some code from Branches/OpenCL to trunk, related to threading and OpenCL:

Added Demos/ThreadingDemo showing how to use the cross-platform btThreadSupportInterface under Windows.
Added Demos/ParticlesOpenCL showing how to run the NVidia particle demo under OpenCL implementations by AMD, NVidia and MiniCL (CPU)

Demos/ParticlesOpenCL/btParticlesSharedTypes.h

@@ -0,0 +1,54 @@
+/*
+Bullet Continuous Collision Detection and Physics Library, http://bulletphysics.org
+Copyright (C) 2006 - 2009 Sony Computer Entertainment Inc. 
+
+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.
+*/
+#ifndef BT_SPHERES_GRID_DEMO_SHARED_TYPES
+#define BT_SPHERES_GRID_DEMO_SHARED_TYPES
+
+struct btSimParams
+{
+	float m_gravity[4];
+	float m_worldMin[4];
+	float m_worldMax[4];
+	float m_cellSize[4];
+	int   m_gridSize[4];
+
+	float m_particleRad;
+	float m_globalDamping;
+	float m_boundaryDamping;
+	float m_collisionDamping;
+
+	float m_spring;
+	float m_shear;
+	float m_attraction;
+	float m_dummy;
+};
+
+struct btInt2
+{
+	int x;
+	int y;
+};
+
+struct btInt4
+{
+	int x;
+	int y;
+	int z;
+	int w;
+};
+
+
+
+#endif
+