Automatically created subtasks

This modification would add an option to specify trigger-tracker(s) on a project. Also, an option to specify automatic-subtask-tracker would be added. If a task with trigger-tracker is created, the subtasks with automatic-subtask-tracker will be created as follows. This feature is to be optional per project.

Subject of subtask: "Custom name" + copy of subject from parent task
Type of task: as defined automatic-subtask-tracker
Status: "New"
Priority: "Normal"
Author: copied from parent task
Project: copied from parent task
Sprint: copied from parent task
Milestone: copied from parent task