Update map min/max for exporting.
Update map min/max for exporting.

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