Add a filter "between" for dates and priority

[Cito]

A new filter operator between could sometimes be useful, so that you can write filters like

happens between past sunday and next sunday

This would be just syntactic sugar for

(happens after past sunday) OR (happens on past sunday)
(happens before next sunday) OR (happens on next sunday)

I.e. the between should be interpreted as being inclusive, because it is done like that in SQL and we don't want to confuse people who already know SQL.

Maybe it would also make sense to support this operator on priorities, like

priority between none and medium

And once we have custom score functions, this could also extend to them, like

urgency score between 3.5 and 4

Again, this is only syntactic sugar and nice to have, similar to #124, it can already be done using multiple filters and boolean expressions.

[claremacrae]

Many thanks for logging this.

I.e. the between should be interpreted as being inclusive, because it is done like that in SQL and we don't want to confuse people who already know SQL.

I'm unsure about that. I think there's a bit of a tension there between those with technical knowledge of SQL versus English speakers knowing the conventional meaning of 'between', which is not inclusive.

I wonder if there is a way to make the behaviour explicit - perhaps with keywords for both inclusive and exclusive, and require the user to specify which they want.

[Cito]

You may be right. I also think the common meaning is to be not inclusive. (Wasn't a design goal of SQL to be readable by humans?)

Yes, we could add an extra clause to make this explicit.