Add auto language detection

[mountaincastle47]

if you can add i will be very thankful :)

[OneMoreGres]

AFAIK tesseract library can recognize multiple languages and auto detect it for each character. But it would significantly increase processing time and could lead to mix of languages within a single word. Maybe there will be a better way in the future.

For now you can save areas with their own languages if their position is known and doesn't change.