add improved btGeneric6DofSpring2Constraint, thanks to Puhr Gabor and Tamas Umenhoffer!

improved the new demo testbed (work-in-progress)
add basic Lua demo, import URDF test, STL import, obj import

Demos/SerializeDemo/SerializeSetup.cpp

@@ -0,0 +1,21 @@
+#include "SerializeSetup.h"
+#include "../Extras/Serialize/BulletWorldImporter/btBulletWorldImporter.h"
+
+SerializeSetup::SerializeSetup()
+{
+    
+}
+SerializeSetup::~SerializeSetup()
+{
+    
+}
+    
+void SerializeSetup::initPhysics(GraphicsPhysicsBridge& gfxBridge)
+{
+    this->createEmptyDynamicsWorld();
+    gfxBridge.createPhysicsDebugDrawer(m_dynamicsWorld);
+    m_dynamicsWorld->getDebugDrawer()->setDebugMode(btIDebugDraw::DBG_DrawWireframe);
+    btBulletWorldImporter* importer = new btBulletWorldImporter(m_dynamicsWorld);
+    const char* filename = "testFile.bullet";
+    importer->loadFile(filename);
+}