New task dialog

Hi,
I've made a new task dialog (among other things) I would like you to 
check out, especially Mark :)
I've added a scheduling type of 'FixedInterval' where you can define a 
fixed start- and enddatetime for your task. If the time-part of both 
datetimes are 0, the end date is interpreted as 'end of day' and 
hence, duration = end - start + 1.

Default values for a task can be set in the config dialog.

(Expect to find some things not right, don't really have time to test 
this now ;)

Have a nice weekend!
-- 
Mvh,
Dag Andersen