more fixes towards working convex-convex, in case of (too) many edge-edge cases:

1) sample directions over a unit sphere and
2) add a contact, using mpr
add missing bullet.pc.cmake file (for old Bullet 2.x)

Demos3/GpuDemos/rigidbody/Bullet2FileDemo.cpp

@@ -18,6 +18,7 @@ void Bullet2FileDemo::setupScene(const ConstructionInfo& ci)
 	b3Assert(ci.m_instancingRenderer);
 
 	const char* fileName="data/testFile.bullet";
+//const char* fileName="data/testFileFracture.bullet";
 
 	FILE* f = 0;