The tiny, ruggedly beautiful Balkan state has something for everyone.Alexandra Goss When you request €100 from a cash machine in Porto Montenegro, it spits out a crisp €100 note, which tells you pretty much all you need to know about the Balkan millionaires’ playground. In this superyacht marina, Montenegro’s answer to Monaco, the shops are spendy — Alexander McQueen, Chopard, Valentino —...