API CHANGE:
Allowing NULL as message public pointer (using default) in calls to
msg_serialize(), msg_header_add(), msg_header_prepend(),
msg_header_add_dup(), msg_header_add_dup_as(), msg_header_add_make(),
msg_header_add_str(), msg_header_insert(), msg_header_remove(),
msg_header_remove_all(), and msg_header_replace().

darcs-hash:20060317124545-65a35-7fb9a54b61290db26d445feebbbc8ecb26b96479.gz