dbus-cxx 0.3.3 released

This release introduces a new macro DBUS_CXX_ITERATOR_SUPPORT to support types that are not natively supported by dbus-cxx but can be static_cast<> to a supported type. This is typically most useful for supporting enumeration types.

dbus-cxx-xml2cpp has been modified to use DBUS_CXX_ITERATOR_SUPPORT to support castable types when generating proxy and adapter interfaces for both methods and signals.

The example computer-is-a has been modified to demonstrate the use of dbus-cxx-xml2cpp and enums with both methods and signals.