Search not case-insensitive for non-ascii characters (e.g. German Umlauts)

[Eucyon]

Behavior for ASCII characters:

echo -e "uber\n Uber\n"|fzy
> u
uber
 Uber

When you search for lowercase "u", both "uber" and "Uber" are shown.

Behavior for non-ASCII characters:

echo -e "über\n Über\n"|fzy
> ü
über

When you search for lowercase "ü", only "über" is found.

[mustafa0x]

Similarly, Arabic has a few letters that should match each other, e.g. ا == أ for searching purposes.