The bugdoc has 3 items in the picture strip and PowerPoint laid this out
as a single column with 3 rows (as a snake algorithm). We used to put
the first two items to the first row and the third item to the second
row.

Improve out layout by taking into account what aspect ratio the child
algorithms request: this way it's obvious that we should use a single
column in case we have a large enough aspect ratio and few enough items.

(PowerPoint also uses multiple columns without the aspect ratio
request.)

Change-Id: I9f1158c04c665fc6a2c85e4ac3a1ed363b1c75fb
Reviewed-on: https://gerrit.libreoffice.org/68370Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins