Feature: lookup TO address on import

When importing messages (qwk, ftn, nntp), and there is a reference to a prior message, if the TO: name matches the start of the FROM name from the referenced/replied message, copy the FROM net_address/type on the referenced/reply-to message as the TO net address for the new message.

This can help with resolving/looking up profile information. For example a future companion web-service for voting or profile details (user avatars, etc).