org-indent: remove refresh timer
* lisp/org-indent.el (org-indent-fix-section-after-idle-time): remove
variable.
(org-indent-initialize): remove timer.
(org-indent-add-properties): refactor code.
(org-indent-refresh-subtree, org-indent-refresh-section,
org-indent-refresh-buffer,org-indent-set-initial-properties): remove
functions.
(org-indent-deleted-headline): new variable.
(org-indent-notify-deleted-headline,org-indent-refresh-maybe): new
functions.
(org-indent-mode): insert new functions into a hook.