#412 Unicode issue

Dear sir,

There seems to be an inherent Unicode issue in OpenSong, especially in set mode searches.
I have brought this issue to Opensong team's attention several times in the past and I cherished the hope of the issue being resolved in the next versions to no avail.

Specifically, I am having a problem with Turkish characters İ, Ş, ş

Kindly let me know if the issue stems from a technical impossibility or not.