Test support for pointer payloads and polymorphic payloads. Both are intended

to be used with shared pointers, such as boost::shared_ptr, which introduces
a dependency on boost. We plan to use shared_ptr in other places as well, and
other bits of boost too. It seems at least kdedu, kdevelop and lots of
stuff in playground already use boost, so maybe we should face realities and
make that dependency kde-wide.

svn path=/trunk/KDE/kdepim/akonadi/libakonadi/; revision=657849