The existence of QAbstractItemModel virtual methods
moveRow, moveColumn, moveRows, and moveColumns
is implied by the existence of
beginMoveRows, endMoveRows, beginMoveColumns and endMoveColumns.
However, these were not actually provided by QAbstractItemModel.
With this change, subclasses can implement support for moving rows
and columns following the same pattern as for insert* and remove*.
Change-Id: Iad8b2223d4b9303abb6459c174a82ffed71a0fdf
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>