Don't perform proxy resolution when not needed (slows down startup and preferences save of instances frequently switching between "no proxy" and "manual proxy" if the proxy cannot be resolved)

git-svn-id: http://josm.openstreetmap.de/svn/trunk@6348 0c6e7542-c601-0410-84e7-c038aed88b3b
Merge branch 'master' into mirror