Huge engine change, replace all std::shared_ptrs

Create a new shared pointer type stdext::shared_object_ptr and stdext::shared_obj
using boost::intrusive_ptr

Advantages:
 * half memory usage
 * faster and lightweight

Disadvantages:
 * using weak_ptr is not supported anymore
 * compiling seems slower

src/framework/sound/soundbuffer.h

@@ -27,7 +27,7 @@
 
 #include <framework/util/databuffer.h>
 
-class SoundBuffer
+class SoundBuffer : public stdext::shared_object
 {
 public:
     SoundBuffer();