org-pcomplete: Fix completion for file options
* lisp/org.el (org-options-keywords): Add missing colons.
* lisp/org-macs.el (org-default-options): Removed function.
* lisp/org-pcomplete.el (org-command-at-point): Fix bug with some file
options.
(pcomplete/org-mode/file-option/x): Removed macro.
(pcomplete/org-mode/file-option): Refactor code.
(pcomplete/org-mode/file-option/author,
pcomplete/org-mode/file-option/date,
pcomplete/org-mode/file-option/title,
pcomplete/org-mode/file-option/tags,
pcomplete/org-mode/file-option/select_tags,
pcomplete/org-mode/file-option/priorities,
pcomplete/org-mode/file-option/language,
pcomplete/org-mode/file-option/filetags,
pcomplete/org-mode/file-option/exclude_tags,
pcomplete/org-mode/file-option/email): New functions.