Adjust the 'z' value for tile layers so that they work on devices with low resolution z-buffers.
Adjust the 'z' value for tile layers so that they work on devices with low resolution z-buffers.

Specifically, on Chrome on Android (current version), using too small a z-value results in the layers flickering.

Kitware/geojs,Kitware/geojs,OpenGeoscience/geojs,Kitware/geojs,OpenGeoscience/geojs,OpenGeoscience/geojs