base: port.tcl: Don't show portundocumented(7) for non-existant actions, support port help $topic for topics from section 5 and 7
base: port.tcl: Don't show portundocumented(7) for non-existant actions, support port help $topic for topics from section 5 and 7

git-svn-id: 620571fa9b4bd0cbce9a0cf901e91ef896adbf27@134986 d073be05-634f-4543-b044-5fe20cf6d1d6

danchr/macports-base,danchr/macports-base,neverpanic/macports-base,macports/macports-base,macports/macports-base,neverpanic/macports-base