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/ParticlesDemo.h

@@ -0,0 +1,128 @@
+/*
+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 SPHERES_GRID_DEMO_H
+#define SPHERES_GRID_DEMO_H
+
+#define USE_BULLET_BODIES 0
+
+///enable one or both options (NVidia profiler doesn't support multi-OpenCL context)
+#define INTEGRATION_DEMO 1
+#define SPHERES_DEMO 1
+
+#include "DemoApplication.h"
+#include "LinearMath/btAlignedObjectArray.h"
+#include "BulletDynamics/Dynamics/btDiscreteDynamicsWorld.h"
+
+#include "btParticlesDynamicsWorld.h"
+
+class btBroadphaseInterface;
+class btCollisionShape;
+class btOverlappingPairCache;
+class btCollisionDispatcher;
+class btConstraintSolver;
+struct btCollisionAlgorithmCreateFunc;
+class btDefaultCollisionConfiguration;
+#include "../OpenGL/GlutDemoApplication.h"
+
+
+///BasicDemo is good starting point for learning the code base and porting.
+class ParticlesDemo : public GlutDemoApplication
+{
+
+	class GL_DialogDynamicsWorld* m_dialogDynamicsWorld;
+	//keep the collision shapes, for deletion/cleanup
+	btAlignedObjectArray<btCollisionShape*>	m_collisionShapes;
+
+	btBroadphaseInterface*	m_broadphase;
+
+	btCollisionDispatcher*	m_dispatcher;
+
+	btConstraintSolver*	m_solver;
+
+	btDefaultCollisionConfiguration* m_collisionConfiguration;
+
+	btOverlappingPairCache* m_pairCache;
+
+	int m_mouseButtons;
+	int m_mouseOldX;
+	int m_mouseOldY;
+
+	int m_argc;
+	char** m_argv;
+
+	public:
+
+		int m_drawGridMode;
+		int m_GpuCpuTogglePtr;
+
+	btParticlesDynamicsWorld* m_pWorld;
+	
+
+	// shader
+	GLuint				m_shaderProgram;
+
+	ParticlesDemo(int argc, char** argv)
+	{
+		m_argc = argc;
+		m_argv = argv;
+		m_drawGridMode = 0; 
+		m_GpuCpuTogglePtr = SIMSTAGE_NONE;
+		m_dialogDynamicsWorld = 0;
+	}
+	virtual ~ParticlesDemo()
+	{
+		exitPhysics();
+	}
+	void	initPhysics();
+
+	void	exitPhysics();
+
+	virtual void clientMoveAndDisplay();
+
+	virtual void displayCallback();
+
+	virtual void keyboardCallback(unsigned char key, int x, int y);
+
+	virtual void clientResetScene();
+
+	virtual void mouseFunc(int button, int state, int x, int y);
+	virtual void	mouseMotionFunc(int x,int y);
+	virtual	void reshape(int w, int h);
+/*
+	static DemoApplication* Create()
+	{
+		SpheresGridDemo* demo = new SpheresGridDemo;
+		demo->myinit();
+		demo->initPhysics();
+		demo->m_mouseButtons = 0;
+		demo->m_mouseOldX = 0;
+		demo->m_mouseOldY = 0;
+		return demo;
+	}
+*/
+
+	void outputDebugInfo(int & xOffset,int & yStart, int  yIncr);
+	
+
+	virtual void renderme();
+	virtual void myinit();
+	void init_scene_directly();
+
+};
+
+
+#endif // PARTICLES_DEMO_H
+