ENH: Issue the database upgrade command in UTF-8, like the rest of commands.
ENH: Read free text DICOM fields from the database using a special function to convert them to QString. This function first interprets the given text as UTF-8, and if the QString contains a replacement character (indicating the text wasn't valid UTF-8), then it is interpreted as Latin-1 instead.

This change is necessary to correctly read database records created with previous versions of Starviewer, when all texts were saved in Latin-1.
COMP: Remove unused variable.