[Development] New QTextDocument feature: CSS-style table cell border formatting

[Nils Jeisecke]

Hi list,

the existing QTextDocument table style options are rather lackluster.
It's basically "ugly grid" (resembling ancient 1998's html tables) or
"no grid".

As we needed some more flexibility we've implemented a subset of the
CSS table cell border formatting including a border-collapse mode.
This includes correct pagination (border line continuation) and
repeated header rows suitable for printing.

We've also added support for a subset of the CSS border styles
(limited to TD elements) in the HTML importer and exporter so that
it's possible to use Qt's TextEdit example for trying the new
functionality.

I'd like to invite anyone interested to have a look at this change request:

https://codereview.qt-project.org/#/c/126950/

Any feedback and hints on how to add reasonable auto tests will be appreciated.

Thanks

Nils