add editorconfig file to a3 root directory
add editorconfig file to a3 root directory

liqd/adhocracy3.mercator,liqd/adhocracy3.mercator,liqd/adhocracy3.mercator,liqd/adhocracy3.mercator,liqd/adhocracy3.mercator,liqd/adhocracy3.mercator,liqd/adhocracy3.mercator