(Advanced Calendar/Diary Usage): Tweak some menu descriptions.

(Advanced Calendar/Diary Usage): Tweak some menu descriptions.
(Calendar Customizing): Tweak layout description.
Move calenday-today-marker and calendar-today face to the other
markers.  Condense calendar-star-date and calendar-mark-today description.
(Holiday Customizing): Add oriental and solar holidays.
Add index entries for Baha'i, Christian, Hebrew and Islamic holidays.
Fix holiday-float description.  Use zerop in examples.  Be less verbose.
(Date Display Format): Change ISO format.  Be less verbose.
(Diary Customizing): Mention day and month abbrev arrays.
Mention the date-form variables by name.  Update European example.
(Non-Gregorian Diary): Change node name.  Mention Baha'i functions.
Condense examples.  Mention diary-entry-symbols by name.
Condense table for insertion commands.
(Fancy Diary Display): Mention diary-include-string and
diary-sexp-entry-symbol.  Condense example.  Add Chinese, Coptic,
Ethiopic, Persian date functions.  Condense descriptions.