calendar.el: Add new faces, and day-header-array

* lisp/calendar/calendar.el (calendar-weekday-header)
(calendar-weekend-header, calendar-month-header): New faces.
(calendar-day-header-construct): New function.
(calendar-day-header-width): Also :set calendar-day-header-array.
(calendar-american-month-header, calendar-european-month-header)
(calendar-iso-month-header): Use calendar- faces.
(calendar-generate-month):
Use calendar-day-header-array for day headers; apply faces to them.
(calendar-mode): Check calendar-font-lock-keywords non-nil.
(calendar-abbrev-construct): Add optional maxlen argument.
(calendar-day-name-array): Doc fix.
(calendar-day-name-array, calendar-abbrev-length)
(calendar-day-abbrev-array):
Also :set calendar-day-header-array, and maybe redraw.
(calendar-day-header-array): New option. 
(calendar-font-lock-keywords): Use calendar-day-header-array,
and calendar- faces.  Make obsolete.
(calendar-day-name): Add option to use header array.

* etc/NEWS: Mention this.

Fixes: debbugs:15007

1 files changed, 7 insertions, 0 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 6c0c81dc0ae..4758a4da31f 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -233,6 +233,13 @@ The default separator is changed to allow surrounding spaces around the comma.
 
 ** Calendar and Diary
 
+*** New faces: `calendar-weekday-header', `calendar-weekend-header',
+`calendar-month-header'.
+
+*** New option `calendar-day-header-array'.
+
+*** The variable `calendar-font-lock-keywords' is obsolete.
+
 +++
 *** New variable `diary-from-outlook-function', used by the command
 `diary-from-outlook'.