Versioning and cursors

[Tuomas Lukka <lukka@xxxxxxxxxxx>]

I think I've got it: as I added to Spec, the way to be consistent is to
have d.cursor represent the cursor dimension at aonly the current moment.
For past moments, d..cursor-past is used (which is simply implied by the
past d.cursor). What do you think: does this realy work as well as I think
it does or am I missing something?

	Tuomas