Including: added ID field with setters, removed final fields and added their setters, removed createDate because it is an useless attribute.

This reverts commit 2586da8d.
The change was done before the transition from TabbedPane to ListHolder as Action data source, therefore it is no longer necessary.

Might also detect TaskStatus.IN_PROGRESS in a similar fashion using subtask list.

Inspired by `CircleColorPanel`

For better visual clarity.

Instead now, the Task list panels have a border around them + their counter.

Also makes it clear which popup menu utilizes the superiorTaskLisk parameter.

This commit also ultimately removes Utilities.java as there would be no methods left in there, and the *PopupMenu inheritance hierarchy since it has been superseded.