Act on the .udc session, off-time and band-change settings

Four settings were read by nothing.

MultipleSessions = 0000/30 runs the contest in half-hour sessions from
00:00 UTC. The session is part of the dupe key, so a station worked in
an earlier one may be worked again, and ResetMultsEverySession and
ResetSNEverySession start the multipliers and the serial numbers over.

DupeQSOMinutesAgo is the other way back to a station: after so many
minutes rather than in the next session. The log holds the time of the
last contact per dupe key instead of only the key, and the setting's
IgnoreBand and ThisMode decide the scope, because a file that uses it
turns DupeType off.

MinimumOffTime drives the time on and time off the score summary now
shows under the score, and beside them are the band changes made against
the allowance for a contest that limits them. N1MM's countdown for the
minutes you have to stay on a new band needs its info window and is not
here.

UdcFile.Flag now takes 1 and 0 as well as True and False, which is what
these settings are written as and what N1MM reads.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RoGtneMQaz4M9w7Kk49AVD

docs/unfinished.md

@@ -111,7 +111,9 @@ with the CW and SSB running of the contest.
 `.udc` settings that are still passed over. `MultiplierBands` and
 `QsoErrorString`, which are about the windows rather than the score.
 `GenericPrintString`, which is the layout of a printed log rather than a
-Cabrillo one.
+Cabrillo one. `SOBandChangeTimerDuration` and `MOBandChangeTimerDuration`, the
+minutes a station has to stay on a new band, which N1MM shows as a countdown in
+its info window; this program has no info window and no countdown.
 
 `MultWindowType` is read as far as the score goes: it names the list a section
 multiplier is checked against. Four of N1MM's lists are held here — the ARRL
@@ -131,11 +133,7 @@ alone, which writes only half of a two-box exchange. Layout 6, the ARRL RTTY
 Roundup line, is not read, and a file asking for it gets the default line; no
 published `.udc` file asks for it, because the Roundup has a contest class of
 its own. `CabrilloFormat = 0` means the sponsor takes no Cabrillo log at all,
-and nothing here stops the operator writing one. The
-session, off-time and band-change settings
-(`MultipleSessions`, `MinimumOffTime`, the `…BandChange…` family,
-`DupeQSOMinutesAgo`) are read by nothing, so a contest with periods is logged
-as one long session.
+and nothing here stops the operator writing one.
 
 N1MM's `.udc` format has no way to say that the exchange itself differs by the
 other station's country. OK/OM DX is written in code for that reason — it asks