Fix the editable delegate in tableview example

We re-interpreted what "model" means in TableView to align it
with what it means for ListView. Unfortunately the example still assume
that "model" refers to the views acual model object and not to the
current item data as it did for listview.

Change-Id: I3457954a622be38500672edb1c0a910d18760947
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>
Take into account icon size when determining button size

When a style calculates the sizeFromContents on a pushbutton it needs to
be informed about the size of the icon on the button.

In oxygen icons with buttons are slightly larger than buttons without.

Change-Id: I2f2d5f08747ad5e6ac0dfb50531c3e7627e9b35f
Reviewed-by: Sebastian Kügler <sebas@kde.org>
Reviewed-by: Marco Martin <mart@kde.org>
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>