Extend oomhelp for address book integration

* src/oomhelp.h (shared_disp_t, MAKE_SHARED, release_disp):
New. Automatically releasing IDispatch pointer.
* src/oomhelp.cpp, src/oomhelp.h (release_disp),
(get_oom_recipients_with_addrEntry, find_user_prop),
(find_or_add_text_prop): New.

This adds a way to get the recipients with their addresentry
objects. For more complex IDispatch handling we now
have shared_disp_t and MAKE_SHARED to wrap the IDispatch
in an automatically releasing shared pointer.

find_user_prop and find_or_add_text_prop are new
functions to interact with Contact properties.