Feature Request - Active and inactive links.

["Tim O'Callaghan" <tim.ocallaghan@gmail.com>]

This is something i have been pondering for a while, and after
seeing the recent discussion on links from org files, thought i
would put forward for discussion. It is an attempt to kill two
birds with one stone. The first is collaboration, the second is a
selective trigger mechanism for generating Agenda items.

Currently Org mode supports links like:
     http://www.astro.uva.nl/~dominik
     file:/home/dominik/images/jupiter.jpg
     news:comp.emacs
     etc....

I would like to propose the concept of 'Active' links, based on
the above. The idea being that some links are marked such that
when Org is building an agenda, it includes these links as if they
were in the org-agenda-files list.

An active link could be prefixed by a + sign, possibly with
embedded metainformation for the agenda.

Some possible examples:
-  read/write remote org file for collaboration via efs/angeftp
 +file:/me@my-home-machine.com:/home/me/personal.org
- read only remote org file for collaboration in category work
 +work+http://www.astro.uva.nl/~dominik/remote.org
- read only remote ical file of local whats-on information.
 +whatson+ical:http://upcoming.yahoo.com/calendar/v2/place/upI5ACueA5szd_8-

Some thought would need to be put into how agenda handles read
only links. In a collaborating read only situation, a masking or
supplementing mechanism might be needed.

This mechanism could conceivably be used to auto-build
org-agenda-files by traversing the active links.

What do people think?

Tim.