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
* implement draw clipping using opengl stencil buffers
* allow to create Widgets by style name with g_ui.createWidgetByStyle
* styles can now have children widgets
* make proper use of the isNotPathable in pathfinding
* add scrollbar skin
Bruno Minervino