(calendar-version): New function.

(calendar-version): New function.
Adjustments to commentary at top of file.
(diary-entry-marker, calendar-today-marker,
calendar-holiday-marker): Don't autoload them; change definitions
to support monochrome and color workstations.
(calendar-french-date-string,calendar-mayan-date-string): Autoload them.
(calendar-day-of-year-string, calendar-iso-date-string,
calendar-julian-date-string,calendar-islamic-date-string,
calendar-hebrew-date-string,calendar-astro-date-string): New functions
(calendar-print-day-of-year, calendar-print-iso-date,
calendar-print-iso-date,calendar-print-julian-date,
calendar-print-islamic-date,calendar-print-hebrew-date,
calendar-print-astro-day-number): Use them.
(calendar-mode-map): Add mouse support.
(calendar-unmark,mark-visible-calendar-date,calendar-mark-today):
Rewritten.