kfontinst: Fix font list view header alignment and item sizehint

Review Request #123220 - Created April 2, 2015 and submitted - Latest diff uploaded

Daniel Vrátil

I'm not sure the Qt::TextAlignmentRole is even needed (I think it would be better if the KCM obeyed whathever is the current theme default), but it should at least be centered vertically. I guess this wasn't so obvious with Oxygen, but Breeze makes the missing vertical alignment really obvious.

For the SizeHint role, relying on size of a particular random icon if we have a standard method for retrieving default icon size sounds wrong to me. For some reason my system refuses to load dialog-ok icon (so SmallIcon("dialog-ok").size() was returning QSize(0, 0)), which caused all items in the view to have SizeHint QSize(0, 4), making it KCM basically unusable.