add Bullet 2.x constraint solver tests for hinge, with large mass ratio

experiment with Midi controls in PairBenchmark to tune variables (will move it into a utility class, so every demo can easier use it in the future)
fix issue with broadphase, not initializing all pairs properly at pair array overflow

Demos3/bullet2/BasicDemo/MyDebugDrawer.h

@@ -0,0 +1,48 @@
+#ifndef MY_DEBUG_DRAWER_H
+#define MY_DEBUG_DRAWER_H
+
+#include "LinearMath/btIDebugDraw.h"
+
+class MyDebugDrawer : public btIDebugDraw
+{
+	SimpleOpenGL3App* m_glApp;
+	int m_debugMode;
+public:
+
+	MyDebugDrawer(SimpleOpenGL3App* app)
+		: m_glApp(app)
+		,m_debugMode(btIDebugDraw::DBG_DrawWireframe|btIDebugDraw::DBG_DrawAabb)
+	{
+
+	}
+	virtual void	drawLine(const btVector3& from,const btVector3& to,const btVector3& color)
+	{
+		m_glApp->m_instancingRenderer->drawLine(from,to,color);
+	}
+
+	virtual void	drawContactPoint(const btVector3& PointOnB,const btVector3& normalOnB,btScalar distance,int lifeTime,const btVector3& color)
+	{
+	}
+
+	virtual void	reportErrorWarning(const char* warningString)
+	{
+	}
+
+	virtual void	draw3dText(const btVector3& location,const char* textString)
+	{
+	}
+	
+	virtual void	setDebugMode(int debugMode)
+	{
+		m_debugMode = debugMode;
+	}
+	
+	virtual int		getDebugMode() const
+	{
+		return m_debugMode;
+	}
+
+
+};
+
+#endif //MY_DEBUG_DRAWER_H