blw topic: allow up to 10 layers in the layer tree

git-svn-id: https://svn.bgdi.admin.ch/mf-chsdi/trunk/chsdi@3355 e100092c-b5e6-494f-8bdf-19c1ff2a4001
blw topic: allow up to 10 layers in the layer tree

git-svn-id: https://svn.bgdi.admin.ch/mf-chsdi/trunk/chsdi@3356 e100092c-b5e6-494f-8bdf-19c1ff2a4001