2 - Chat: OnTimeout, ExceptReply
3 - handle timeouts in Download
6 - combine SEG reqests up to 32
7 - send info only for first
8 - move seeking to aggr.thr
9 - prepare seglist before start
10 - separate store1.SegSeek -> SegAvail; ReadSeg(base,length,into,rc);
12 - reset Mark on resume
13 - do not update oi.length if unchanged
14 - skip unavailable segments
15 - upmgr: send avalable subsegment base
16 ? Download request random subsegment
17 (distribution + exercise for recombinator)