org.el: Use `user-error' instead of `error'

org.el: Use `user-error' instead of `error'

* org.el (org-flag-drawer, org-hide-block-toggle)
(org-goto-left, org-goto-right, org-promote)
(org-paste-subtree, org-narrow-to-block, org-sort-entries)
(org-insert-link, org-offer-links-in-entry, org-open-file)
(org-refile, org-refile-get-location)
(org-refile-check-position, org-prepare-dblock, org-todo)
(org-auto-repeat-maybe, org-show-todo-tree, org-sparse-tree)
(org-occur, org-priority, org-scan-tags)
(org-get-tags-string, org-property-action, org-set-effort)
(org-entry-put, org-insert-drawer)
(org-compute-property-at-point)
(org-property-next-allowed-value, org-evaluate-time-range)
(org-closest-date, org-timestamp-change)
(org-revert-all-org-buffers, org-cycle-agenda-files)
(org-agenda-file-to-front, org-remove-file)
(org-preview-latex-fragment, org-format-latex)
(org-create-math-formula, org-create-formula-image)
(org-speed-command-help, org-check-before-invisible-edit)
(org-modifier-cursor-error, org-hidden-tree-error)
(org-mark-subtree, org-kill-line, org-first-sibling-p)
(org-up-element, org-down-element)
(org-drag-element-backward, org-drag-element-forward)
(org-unindent-buffer, org-speedbar-set-agenda-restriction):
Use `user-error' instead of `error'.