Cal compatible interface

[fzerorubigd]

Change the option parsing to a cal(1) compatible interface. The change is a backward incompatible change.

cal -h 

Usage:
 cal [options] [[[day] month] year]
 cal [options] <timestamp|monthname>

Display a calendar, or some part of it.
Without any arguments, display the current month.

Options:
 -1, --one             show only a single month (default)
 -3, --three           show three months spanning the date
 -n, --months <num>    show num months starting with date's month
 -S, --span            span the date when displaying multiple months
 -s, --sunday          Sunday as first day of week
 -m, --monday          Monday as first day of week
 -j, --julian          use day-of-year for all calendars
     --reform <val>    Gregorian reform date (1752|gregorian|iso|julian)
     --iso             alias for --reform=iso
 -y, --year            show the whole year
 -Y, --twelve          show the next twelve months
 -w, --week[=<num>]    show US or ISO-8601 week numbers
     --color[=<when>]  colorize messages (auto, always or never)
                         colors are enabled by default

 -h, --help            display this help
 -V, --version         display version

For more details see cal(1).