Feature Request: Support Subtasks

[passuf]

Up-score habits if a Subtask of a Task in a connected List is completed.

The only relevant difference in the received payload is (compared to a completed Task):
"type": "subtask" instead of "type": "task"

Handle this case in the webhook view, then up-score the Habit. The question is, if the Habit should be up-scored by the same value as a Task, or, if Habitica allows, only e.g. half the value.