Unicode 6.2.0 introduces the notion of "Title case", making the trio of:

"Lower case" => "Title case" => "Upper case"

Example:
01c6  01c5  01c4
dž     Dž     DŽ

This means that functions such as "capitalize" are wrong because they make the assumption that "Capitalize" == "Uppercase"

Also, the tests such as:

if(std.uni.isLower(c))
    c = std.uni.toUpper(c);

are wrong, as non lower case characters may have upper case representations...