I would like to be able to create a report which only shows tasks which are due by a certain date:

duedate <= dueDateTo

It should be possible to specify dueDateTo as a specific value, or a rolling value of x days in the future/past:

tasks due this week: duedate <= +7d
tasks overdue by 3 days: duedate <= -3d

It should be possible to specify whether tasks with no due date are included or excluded:

tasks possibly due this week: duedate <= +7d include (i.e. duedate <= +7d OR duedate == null)
tasks definitely due this week: duedate <= +7d exclude