Add EPA penetration depth solver support to bullet multithreaded.

Update SubSimplexConvexCast algorithm used in bullet multithreaded.

Extras/BulletMultiThreaded/SpuNarrowPhaseCollisionTask/SpuGjkEpa2.h

@@ -0,0 +1,38 @@
+#ifndef _68DA1F85_90B7_4bb0_A705_83B4040A75C6_
+#define _68DA1F85_90B7_4bb0_A705_83B4040A75C6_
+#include "BulletCollision/CollisionShapes/btConvexShape.h"
+
+///btGjkEpaSolver contributed under zlib by Nathanael Presson
+struct	SpuGjkEpaSolver2
+{
+struct	sResults
+	{
+	enum eStatus
+		{
+		Separated,		/* Shapes doesnt penetrate												*/ 
+		Penetrating,	/* Shapes are penetrating												*/ 
+		GJK_Failed,		/* GJK phase fail, no big issue, shapes are probably just 'touching'	*/ 
+		EPA_Failed,		/* EPA phase fail, bigger problem, need to save parameters, and debug	*/ 
+		}		status;
+	btVector3	witnesses[2];
+	btVector3	normal;
+	};
+
+static int		StackSizeRequirement();
+
+
+static bool		Penetration(void* shapeA,
+							SpuConvexPolyhedronVertexData* convexDataA,
+							int shapeTypeA,
+							float marginA,
+							const btTransform& xformA,
+							void* shapeB,
+							SpuConvexPolyhedronVertexData* convexDataB,
+							int shapeTypeB,
+							float marginB,
+							const btTransform& xformB,
+							const btVector3& guess,
+							sResults&	results);
+};
+
+#endif