[XeTeX] Problem with Turkish dotted I (U+0130) in headers

[Arthur Reutenauer]

>> However, \uccode`\i=`\İ gives the intended result but doesn't create
>> problems only because I'm working in a monolingual document, such type of
>> capitalization should be restricted to Turkish.
>
> Yes, it should be done in polyglossia. I am sending Cc to Arthur Reutenauer.

  Thanks, Zdenku.  I read the list, you don't need to cc me.

  I will add that to gloss-turkish.ldf; strange it hadn't been done from
the beginning, though!

	Arthur