nwwTile: avoid unnecessary QImage copy.
nwwTile: avoid unnecessary QImage copy.

quannt24/marble,tzapzoor/marble,tucnak/marble,rku/marble,tzapzoor/marble,utkuaydin/marble,Earthwings/marble,adraghici/marble,adraghici/marble,Earthwings/marble,utkuaydin/marble,tucnak/marble,AndreiDuma/marble,oberluz/marble,quannt24/marble,tzapzoor/marble,utkuaydin/marble,David-Gil/marble-dev,adraghici/marble,rku/marble,oberluz/marble,AndreiDuma/marble,tzapzoor/marble,rku/marble,David-Gil/marble-dev,tucnak/marble,utkuaydin/marble,probonopd/marble,tzapzoor/marble,tucnak/marble,tucnak/marble,quannt24/marble,David-Gil/marble-dev,adraghici/marble,quannt24/marble,probonopd/marble,rku/marble,tzapzoor/marble,AndreiDuma/marble,utkuaydin/marble,probonopd/marble,adraghici/marble,tzapzoor/marble,AndreiDuma/marble,Earthwings/marble,tzapzoor/marble,oberluz/marble,AndreiDuma/marble,oberluz/marble,oberluz/marble,quannt24/marble,probonopd/marble,AndreiDuma/marble,rku/marble,probonopd/marble,utkuaydin/marble,oberluz/marble,quannt24/marble,David-Gil/marble-dev,rku/marble,tucnak/marble,Earthwings/marble,tucnak/marble,quannt24/marble,David-Gil/marble-dev,probonopd/marble,Earthwings/marble,probonopd/marble,David-Gil/marble-dev,adraghici/marble,Earthwings/marble