org: Grouptags not unique and can contain regexp
* lisp/org.el (org-tags-expand): Grouptags can have regular expressions as
"sub-tags".
The regular expressions in the group must be marked up within { }.
Example use:
: #+TAGS: [ Project : {P@.+} ]
Searching for the tag Project will now list all tags also including
regular expression matches for P@.+. Good for example if tags for a
certain project is tagged with a common project-identifier,
i.e. P@2014_OrgTags.
* lisp/org.el (org-tag-alist) : New symbols for grouptags when the
tags in the group don't have to be distinct on a heading.
Grouptags had to previously be defined with { }. This syntax is
already used for exclusive tags and Grouptags need their own,
non-exclusive syntax. This behaviour is achieved with [ ]. Note: {
} can still be used also for Grouptags but then only one of the
given tags can be used on the headline at the same time. Example:
[ group : sub1 sub2 ]
Grouptags also are not filtered when setting up tags. This means
they can exist multiple times in org-tag-alist list. It will be
usable if nesting of grouptags is ever to become reality.
There is a slightly annoying side-effect when setting tags in that a
tag which is both a part of a grouptag and a grouptag of it's own
will get multiple key-choices in the selection-UI.
* lisp/org.el (org--setup-process-tags): Adaption for the added syntax
for non-distinct grouptags.
* lisp/org.el (org-fast-tag-selection): Add support for the added,
non-unique, grouptag-syntax. Minor (if ...) to (when ...) refactor.