Move defcustoms to start.

Move defcustoms to start.
(diary-include-string, diary-list-include-blanks)
(diary-glob-file-regexp-prefix, diary-face, diary-face-attrs)
(diary-file-name-prefix, diary-file-name-prefix-function)
(sexp-diary-entry-symbol, list-diary-entries-hook)
(mark-diary-entries-hook, nongregorian-diary-listing-hook)
(nongregorian-diary-marking-hook, print-diary-entries-hook):
Move here from calendar.el.
(diary-face): Make it a defcustom, and mark as obsolete.
(top-level): No need to require cal-hebrew, cal-islam when compiling.
(calendar-hebrew-month-name-array-leap-year)
(calendar-islamic-month-name-array, calendar-bahai-month-name-array):
Define for compiler.
(diary-font-lock-keywords): Use format rather than concat. Add
bahai-diary-entry-symbol.