Task sync: use time filter?

[rfc2822]

Currently, DAVx5 uses REPORT calendar-query (component filter: VTODO) without time filter for task synchronization. I think the reason was that some servers don't return tasks without time at all. On the other side, users have to delete their tasks from time to time to keep it scaling.

I wonder

• whether current servers process the time filter for tasks/journals correctly,
• whether we should use the time filter for tasks/journals too,
• maybe add an option to the past event time limit: "use past event time limit for tasks, too" (default: on)?