(calendar-cursor-to-nearest-date): Use or, when. Move definition before use.

(calendar-cursor-to-nearest-date): Use or, when.  Move definition before use.
(calendar-cursor-to-visible-date): Move definition before use.
(calendar-scroll-left): Use unless and zerop.  Combine lets into one,
and place inside the conditional.
(calendar-forward-day): Simplify.
(calendar-end-of-month): Use unless.
(calendar-goto-day-of-year): Doc fix.
Relocate obsolete aliases after their replacements.