Changing priorities in a list by drag-n-move of bullet points

### What
Include a feature allowing of simple change of the order in a list by drag-n-move of bullet points / line items.

### Why
To enable a convinient way of prioritizing of line items in a list, e.g. in task lists to move the tasks to do next to the top and done tasks to the bottom of the list.

### How
On mobile devices the most intuitive would be to point on a line item with a finger, hold awhile and then move it across the list while still holding and finally release the hold to place the line item at its new position.
An additional feature would be to allow to mark and move multiple line items at once.

[Type] Enhancement

The issue does not name any files, tests, or entry points. Start by locating the Android screen that renders editable lists and the code that saves item order; done means a line item can be moved by touch and its new position persists, with the scope of multi-item movement clarified.

Written by the indexing model from the issue text.