Special-case country codes and address set patterns in EntryNodes
Right now, Tor only lets you specify EntryNodes verbatim: you can say "I want my entry nodes to be $12345 and FriendlyNode1", but you can't say "I want my entry nodes to be in {de} and {gb} and 18.0.0.0/8."
This limitation exists because of how Tor implements EntryNodes: it set your guard nodes equal to the set of all members of EntryNodes. This make sense if EntryNodes is a pure list of nodes, but when it contains stuff like {de} and {gb}, that probably isn't what you want. Instead, you want your guard nodes to be selected from among the set of EntryNodes.