title: Confusing ToUpper and ToTitle
body: <p>Is there any difference between the <a href="http://golang.org/src/pkg/unicode/letter.go#L248" rel="noreferrer">ToUpper</a> and the <a href="http://golang.org/src/pkg/unicode/letter.go#L270" rel="noreferrer">ToTitle</a> function?</p>