Manual sorting of tasks within a list

[marbetschar]

Problem

Right now its not possible to modify the sort order of individual tasks in a list.

Proposal

It should be possible to re-arrange tasks within a list.

Prior Art (Optional)

Tasks already supports displaying custom sort order within a list using the X-APPLE-SORT-ORDER sort property. This custom property is used by Apple Reminders and is also supported by Nextcloud Tasks:

• Added support for X-APPLE-SORT-ORDER #198

There was a PR for Gtk3 which shows whats involved from the EDS point of view:

• Sort Tasks using Drag & Drop #217