Update and reformat copyright.

Update and reformat copyright.
(Calendar/Diary): Menu now only on Mouse-3, not C-Mouse-3.
(Holidays): Move view-calendar-holidays-initially,
mark-holidays-in-calendar here from emacs-xtra.
(Diary): Refer to `diary-file' rather than ~/diary.
(Diary Commands): Rename node to "Displaying the Diary".
(Displaying the Diary): Move view-diary-entries-initially,
mark-diary-entries-in-calendar here from emacs-xtra.
(Appointments): Move appt-display-mode-line, appt-display-duration,
appt-disp-window-function, appt-delete-window-function here from
emacs-xtra.