add_type_handler_full

This function connects into the type handling of the Client.

Every new menuitem that comes in immediately gets asked for its properties. When we get those properties we check the 'type' property and look to see if it matches a handler that is known by the client. If so, the newfunc function is executed on that Menuitem. If not, then the DbusmenuClient: DbusmenuClient:new-menuitem signal is sent.

In the future the known types will be sent to the server so that it can make choices about the menu item types availble.

Parameters:

this	Client where we're getting types coming in
type	A text string that will be matched with the 'type' property on incoming menu items
newfunc	The function that will be executed with those new items when they come in.
destroy_func	A function that is called when the type handler is removed (usually on client destruction) which will free the resources in user_data.
user_data	Data passed to newfunc when it is called

Returns:

If registering the new type was successful.