(org-agenda-custom-commands): New option.

(org-agenda-custom-commands): New option.
	(org-agenda): Offer custom commands on splash screen.
	(org-make-tags-matcher): Parser for Boolean logic added.
	(org-agenda-set-tags): New command.
	(org-agenda-menu, org-agenda-mode-map): Add `org-agenda-set-tags'.
	(org-set-tags): Efficiency improvements.
	(org-auto-align-tags): New option.
	(org-todo, org-demote, org-promote): Realign tags.
	(org-tags-completion-function): Use also "&" and "|" as
	separators.
	(org-org-menu): Agenda commands simplified.