[Development] New class for QtWidgets: ColumnResizer

[Aurélien Gâteau]

Hi,

Some time ago I created a class to help keeping columns of widgets to the 
same width across layouts, so that if you have two QGroupBoxes on top of 
each others with form layouts, then you can ensure the label columns of both 
boxes are the same width.

I proposed it for inclusion in the KWidgetsAddons KDE framework, but it was 
pointed out to me that this class could as well go to QtWidgets. You can 
find the code in the KWidgetsAddons review request: 
https://git.reviewboard.kde.org/r/118514/

I'd like to ask if it has a chance to be accepted? Before I start creating a 
branch of QtBase for it and submit it to Gerrit.

Aurélien