remove quitZoom-to-quitRadius settings conversion code
remove quitZoom-to-quitRadius settings conversion code

Since commit 600cd553abfb2f212effbac1e2c07392e3b3cd49 the radius rather than the zoom value is stored in the settings.
This patch removes code which converted the "quitZoom" value into a radius value for maintainance reasons.
So if a user didn't start up Marble for half a year, the "quitZoom" settings value will be lost and a default radius will be used instead.

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