Use `lexical-binding` in all the cal-*.el files

Use `lexical-binding` in all the cal-*.el files

* lisp/calendar/cal-bahai.el: Use lexical-binding.
(calendar-bahai-date-string): Use `calendar-dlet*`.

* lisp/calendar/cal-china.el: Use lexical-binding.
(calendar-chinese-zodiac-sign-on-or-after)
(calendar-chinese-new-moon-on-or-after): Declare `year`.
(calendar-chinese-from-absolute-for-diary)
(calendar-chinese-to-absolute-for-diary)
(calendar-chinese-mark-date-pattern): Avoid dynbound var `date` as
function argument.

* lisp/calendar/cal-coptic.el: Use lexical-binding.
(calendar-coptic-date-string): Use `calendar-dlet*`.
(calendar-ethiopic-to-absolute, calendar-ethiopic-from-absolute)
(calendar-ethiopic-date-string, calendar-ethiopic-goto-date):
Avoid dynbound var `date` as function argument.

* lisp/calendar/cal-french.el: Use lexical-binding.

* lisp/calendar/cal-hebrew.el: Use lexical-binding.
(holiday-hebrew-hanukkah): Don't use the third form in `dotimes`.

* lisp/calendar/cal-islam.el: Use lexical-binding.
(calendar-islamic-to-absolute): Comment out unused vars `month` and `day`.

* lisp/calendar/cal-move.el:
* lisp/calendar/cal-mayan.el:
* lisp/calendar/cal-iso.el: Use lexical-binding.

* lisp/calendar/cal-persia.el: Use lexical-binding.
(calendar-persian-date-string): Use `calendar-dlet*`.

* lisp/calendar/cal-html.el: Use lexical-binding.
(cal-html-insert-minical): Comment out unused var `date`.
(cal-html-cursor-month, cal-html-cursor-year): Mark `event` arg as unused.

* lisp/calendar/cal-menu.el: Use lexical-binding.
(diary-list-include-blanks): Declare var.

* lisp/calendar/cal-x.el: Use lexical-binding.

* lisp/calendar/cal-tex.el: Use lexical-binding.
(diary-list-include-blanks): Declare var.
(cal-tex-insert-days, cal-tex-cursor-week-iso, cal-tex-week-hours)
(cal-tex-weekly-common, cal-tex-cursor-filofax-2week)
(cal-tex-cursor-filofax-daily, cal-tex-daily-page): Declare `date`
as dynbound for the benefit of `cal-tex-daily-string`.