Round AbstractTask to half a day

[lfasani]

This enhancement aims at homogenize the behavior of rounding the startTime and endTime of AbstractTask

currently, the following features round the time with half a day

• the edition of an AbstractTask using the details
• the edition of an AbstractTask in Gantt

Enhancement

This enhancement allows rounding the AbstractTask

• at creation
• when a task is updated due to dependency link

To be coherent, the dependency delay should be rounded to half a day too.

Ideally, the details view should have a dedicated time picker that handle half day increment properly.
Another issue may be created to handle this point.