1. did some work on making talk more intelligent and fixed a>b problem.

2. fixed a nasty problem on input when being hit with full buffers of
data (eg at init time with large lists of node/users on fast links).
3. fixed realtime input filter changing.
4. added announce->talk conversion for routable calls when announces of the
form 'to g1tlh hello' or 'g1tlh hello' appear. This also suppresses similar
announces for users whose callsign is not the one in the announce.