ADD 6 types of boundaries to map_features.xml

ADD 6 types of boundaries to map_features.xml
ADD several boundary types to potlatch.css, including a catch-all
REMOVE way[sport] from potlatch.css (it is only a support tag, should theoretically not be rendered without an accompanying leisure=, amenity= etc.
TODO icons for boundaries in map_features.xml
TODO work out whether the other boundary types are worth supporting (and wtf the difference between boundary=town and place=town is)