cal: added two missing tests

Bigyear and Sep1752 lacked their were missing their last intended tests
along with their expected outputs.

Signed-off-by: Tommi Kyntola <kynde@iki.fi>
cal: added -w|--week for showing week numbers

Added week numbers both in ISO-6801 and North America numbering.
The mode is determined by first day of the week, Monday
for ISO and Sunday for North America mode.

ISO week numbers are defined as the first Thursday being part of week 1.
The North America numbering is defined, at least by gcal, as first Sunday
being in the first week.

Signed-off-by: Tommi Kyntola <kynde@iki.fi>
cal: various tests for week numbers

Current tests were replicated with week numbers
and some additional tests for week numbering corner cases
were added, too.

Signed-off-by: Tommi Kyntola <kynde@iki.fi>
cal: added argument option for -w|--week to display that week

Because many years have two sections of week 52 or 53, the week that
this argument points to is the one that starts during that year (when available).
The week number in argument is also highlighted in addition to possibly visible
current/defined date highlighting.

Signed-off-by: Tommi Kyntola <kynde@iki.fi>
cal: remove optional from short arg -w

The long option --week still has the optional argument as --week=<wnum>

This was suggested on the mailing list by Padraig Brady and I do agree with that.
Actually, the whole idea of --week=<wnum> came from him.

Signed-off-by: Tommi Kyntola <kynde@iki.fi>
cal: fix coding style

 - mostly space around operators
 - split yearly(), move weeknum stuff to append_wnum()

Signed-off-by: Karel Zak <kzak@redhat.com>
tests: add TERM= to all cal(1) tests

Signed-off-by: Karel Zak <kzak@redhat.com>