title: QTableView - not allow user to edit cell
body: <p>I created a QTableView with a QSqlTableModel.
  By standard, double-clicking on the cells will mark them and the user can edit them.
  I want, that the user isn't allowed to do that. He is allowed to mark the whole row by clicking on a single cell, but not to edit the cell.
  How can I do that?</p>