Move completed tasks to bottom

[tgrosinger]

When a task is completed, move it to the bottom of the list in that section.

This should be disableable in the settings.

[tgrosinger]

See also: https://github.com/DahaWong/obsidian-completed-area

[tgrosinger]

I'm probably not going to add this, but I'm open to pull requests if someone wants to help out 🙂