Create a document stack to iterate drawings in the order of their usage

[lordofbikes]

This is to keep up the discussion from #1207.

Expected behavior

Closing a drawing window activates the previous used drawing.
TAB and Shift-TAB iterate documents in the order of their usage.

Observed behavior

Closing a drawing window activates always the first drawing, which is mostly the empty unnamed drawing from start.
TAB and Shift-TAB iterate documents in the fixed order of opening.

Steps to reproduce or sample file

• open multiple drawings in Tab mode
• close the latest or any other Tab
• the first drawing is activated then

This applies to Window mode too, but it is harder to observe.

Operating System and LibreCAD version info

All OS, latest master

As discussed in #1207, it can be irritating, especially when working with multiple drawings, when a drawing is closed and the empty unnamed drawing is activated then.

Because #1207 is fixed now by #1696, the problem is solved for Print Preview and Block Editor.
Anyhow, it would be nice to switch between the drawings in the order of their usage too, similar to other applications where TAB and Shift-TAB iterate documents in forward or reverse usage order.

The last #1207 (comment), from @tonischranz, describes the needed steps very well.