Support for diary sexp timestamps

[unhammer]

I'm guessing this is a long shot, but would it be possible to include events specified with diary sexps in org-ql-select calls, e.g.

** Lunch on last Thursdays of each month 11:00-12:00
     SCHEDULED: <%%(diary-float t 4 (- 1))%>

[alphapapa]

Yes, that should be possible. It would probably be best for it to be optional and disabled by default, because it would preclude some regexp-based optimizations. I probably won't work on this soon, but I'll put it on the list. Thanks.