Revert "open Mapnik XML in new window by default"
Revert "open Mapnik XML in new window by default"

This reverts commit 3214fd3b2c326b99873f22c86d71188b63bedc93.

tizzybec/tilemill,fxtentacle/tilemill,MappingKat/tilemill,Teino1978-Corp/Teino1978-Corp-tilemill,tilemill-project/tilemill,florianf/tileoven,tizzybec/tilemill,florianf/tileoven,nyimbi/tilemill,Teino1978-Corp/Teino1978-Corp-tilemill,fxtentacle/tilemill,fxtentacle/tilemill,MappingKat/tilemill,nyimbi/tilemill,mbrukman/tilemill,MappingKat/tilemill,Zhao-Qi/tilemill,Teino1978-Corp/Teino1978-Corp-tilemill,tilemill-project/tilemill,mbrukman/tilemill,Teino1978-Corp/Teino1978-Corp-tilemill,mbrukman/tilemill,nyimbi/tilemill,MappingKat/tilemill,mbrukman/tilemill,fxtentacle/tilemill,fxtentacle/tilemill,mbrukman/tilemill,tizzybec/tilemill,Zhao-Qi/tilemill,Zhao-Qi/tilemill,paulovieira/tilemill-clima,paulovieira/tilemill-clima,MappingKat/tilemill,nyimbi/tilemill,tizzybec/tilemill,Zhao-Qi/tilemill,paulovieira/tilemill-clima,paulovieira/tilemill-clima,florianf/tileoven,tilemill-project/tilemill,nyimbi/tilemill,Zhao-Qi/tilemill,paulovieira/tilemill-clima,Teino1978-Corp/Teino1978-Corp-tilemill,tizzybec/tilemill