Update copyright notice
Change capital to take a single sector as argument

Capital takes a <SECTS> argument, and picks the first suitable sector
it finds there.  It fails if none can be found, or if the first one
found already is the capital (even when more suitable sectors follow).
Has always worked that way, but never documented.

I don't think the search feature is really useful, and documenting it
isn't worth my while.  Change the command to take a <SECT> argument
instead, as documented.
Make capital fail more nicely when sector is unsuitable

The command fails without an explanation then.  Change it to print
something like "X,Y is not a capital or mountain owned by you."
anti, give, grind take <SECTS> argument, fix their documentation
Fix setsector not to disclose number of landmines to occupier

When the deity sets the number of mines with setsector, the sector
owner (if any) is told the resulting number of mines.  Even for
occupied sectors, where mines belong to the old owner, and thus
shouldn't be disclosed.  Oops.

Fix setsector not to tell the sector owner anything then.
Drop resnoise()'s second parameter

All callers pass the same argument.
Really fix give not to wipe out concurrent updates

give() continues after check_sect_ok() fails.  Clobbers the updates
that made check_sect_ok() fail, triggering a seqno mismatch oops.

Commit b58c37e2 (v4.3.27) claimed to fix this, but actually only
suppressed the generation oops.
Really fix setsector and setres not to wipe out concurrent updates

setsector() and setres() continue after check_sect_ok() fails.
Clobbers the updates that made check_sect_ok() fail, triggering a
seqno mismatch oops.

Commit 04a332a8 (v4.3.27) claimed to fix this, but actually only
suppressed the generation oops.
Take ship cost into account when picking missile interdiction target

Due to a typo, shp_missile_interdiction() picks the admissible target
with highest efficiency instead of the one with highest efficiency *
build cost.

Broken in commit cd8d7423, v4.3.8.
Simplify head_meanwhile()

No functional change.
Really fix accepting connections from "long" IPv6 address

Commit ee01ac19 (v4.3.23) enlarged player member hostaddr from 32 to
46 characters, but missed natstr member nat_hostaddr.  player_main()
copies hostaddr to nat_hostaddr.  Can overrun the destination, but
fortunately just into nat_hostname.

Impact:

* Can makes praddr() print only a suffix of the address.  Used by play
  command, for player messages during login and logout, and for
  logging.

* Can make player_main()'s test for "same address as last time" fail,
  causing extra "Last connection" messages.

* Matching against econfig key privip is not affected.

* Journal event login is not affected.
Simplify lnd_take_casualty()'s land unit retreat code

Bonus: avoids "may be used uninitialized" compiler warnings (the code
was safe despite the warning).