Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Replace hard-coded value by Julian2Gregorian converter function.

Always convert Paskha day from Julian (old) to Gregorian (new) style by
adding 13 days. Bug introduced in 1.13 revision.

Long awaited update to the calendar system:

- Repeating events which span multiple years (because of -A, -B or
just the three days before the end of the year).

- Support for lunar events (full moon, new moon) and solar events
(equinox and solstice, chinese new year). Because of this, the
options -U (UTC offset) and -l (longitude) are available to
compensate if reality doesn't match the calculated values.

MFC after: 1 month

- Remove times.h from C programs that does not manipulate with time at
all.
- Remove pathnames.h from all but io.c since it's the only module that
used these definations.

Revert most part of 200420 as requested, as more review and polish is
needed.

Remove unneeded header includes from usr.bin/ except contributed code.

Tested with: make universe

style(9)ify usr.bin/calendar

PR: bin/118644
Approved by: bde@ (mentor)
MFC after: 1 week

ANSIfy function definitions.
Move some extern declarations to a header file.
Remove an unneeded extern declaration for optarg.

Style improvements recommended by Bruce as a follow up to some
of the recent WARNS commits. The idea is:

1) FreeBSD id tags should follow vendor tags.
2) Vendor tags should not be compiled (though copyrights probably should).
3) There should be no blank line between including cdefs and __FBSDIF.

WARNS=2 fixup (mostly. Some are Hard To Fix(tm), so NO_WERROR is set)
Use __FBSDID().
Sort some headers.

Add missing $FreeBSD$ tags

Includes cleanup
Submitted by: bde

Localize even more.
FIx Orthodox Easter calculation
Better debug output

Allow to configure national Easter names.
Speedup my national months/days handling code.

Localize it
Handle Orthodox Eastern
-Wall cleanup