Move tasks to bugzilla

[Tom Tromey]

I'd like to propose changing how we manage our task list.

Rather than have it on the wiki, I think we should file each task as a
bug in bugzilla.  We would add an "archer" tag to each task.

Then, we could replace the current list on the wiki with a bugzilla
query.

I think this would be somewhat better since it would give us a way to
track who is working on which archer task; and also let us more easily
"accept" existing bugs into archer (by just adding the tag).  This would
also give us a built-in spot to discuss any particulars of a given task,
and a simple way to indicate task dependencies (and even priorities if
we care).

Some of our tasks are a bit vague for a PR; but the vague ones aren't
really tasks so much as long-term goals or wishes.  Those could remain
on the wiki.

Any comments?

Tom