MultiThreaded Demo:

- fixing various race conditions throughout (usage of static vars, etc)
 - addition of a few lightweight mutexes (which are compiled out by default)
 - slight code rearrangement in discreteDynamicsWorld to facilitate multithreading
 - PoolAllocator::allocate() can now be called when pool is full without
     crashing (null pointer returned)
 - PoolAllocator allocate and freeMemory, are OPTIONALLY threadsafe
     (default is un-threadsafe)
 - CollisionDispatcher no longer checks if the pool allocator is full
     before calling allocate(), instead it just calls allocate() and
     checks if the return is null -- this avoids a race condition
 - SequentialImpulseConstraintSolver OPTIONALLY uses different logic in
     getOrInitSolverBody() to avoid a race condition with kinematic bodies
 - addition of 2 classes which together allow simulation islands to be run
   in parallel:
    - btSimulationIslandManagerMt
    - btDiscreteDynamicsWorldMt
 - MultiThreadedDemo example in the example browser demonstrating use of
   OpenMP, Microsoft PPL, and Intel TBB
 - use multithreading for other demos
 - benchmark demo: add parallel raycasting

examples/CommonInterfaces/CommonGraphicsAppInterface.h

@@ -120,7 +120,7 @@ struct CommonGraphicsApp
 	virtual int getUpAxis() const = 0;
 	
 	virtual void swapBuffer() = 0;
-	virtual void drawText( const char* txt, int posX, int posY) = 0;
+	virtual void drawText( const char* txt, int posX, int posY, float size = 1.0f) = 0;
 	virtual void drawText3D( const char* txt, float posX, float posZY, float posZ, float size)=0;
 	virtual void drawTexturedRect(float x0, float y0, float x1, float y1, float color[4], float u0,float v0, float u1, float v1, int useRGBA)=0;
 	virtual int	registerCubeShape(float halfExtentsX,float halfExtentsY, float halfExtentsZ, int textureIndex = -1,  float textureScaling = 1)=0;