*.srt files ignored during folder scan

[rostrovsky]

When folder scan option is used ("Skanuj katalogi") and ignoring files with subtitles present ("Podczas wyszukiwania pomijaj pliki, do których istnieją już napisy") is ON, QNapi ignores existing *.srt files (only *.txt files are detected).

Issue is present in QNapi 0.1.9-snapshot and previous versions.