Instance distance from current

[dmfs]

In #600 we've added an instance status column which allows to distinguish between closed, current and future instances. However, it just occurred to me that we can extend the semantics of this a bit and use the field as a kind of instance number (or distance) with 0 being the "current instance", 1 the next one, 2 the one after the next one, etc. So instance numbers >0 would still denote upcoming instances but with the additional meaning of the distance from the current one. This could be useful in the UI. Since this is much less useful but much harder for closed instances, I propose to keep a "distance" of -1 for all closed instances.

[dmfs]

Since the instance_status column would be superseded by instance_distance, we should override the changes in d0ff43e, so the instance_status column doesn't make it into the next release.

[lemonboston]

I see that this instance number can increases the utility of this field.

What is not clear for me is what is the distinction between the current one 0 and next one 1 for recurrent tasks?
So let's say I have a weekly recurrent task on Wednesday and it's Monday now, what number would the task on Wednesday have?

[dmfs]

If there is no other instance between now and Wednesday, the one on this Wednesday would be 0 and each instance thereafter would have it's number increased by 1 (compared to its predecessor).