Minimize column width: Adjusts the width of the selected columns
to fit the selected content. The table can shrink if necessary,
but will not grow.

(Previously no way to minimize columns. Since
minimizing really can mess up merged cells, enhance my
new calcPreferredColumnWidth function.)

Minimize row height: Adjusts the height of the selected rows
to fit the content, causing the table to shrink.

(The new optimize action functioned as minimize. So this change
tweaks optimize so that it does not reduce the table size. A
followup commit will make it distribute based on largest
minimized row (still without reducing table size), and change
distributed rows to work the way the document states - based
on the largest row.

Change-Id: I807a9cc9e9441a1215539e817b87158afe5a0604
Reviewed-on: https://gerrit.libreoffice.org/61472
Tested-by: Jenkins
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>