Make language guessing optional

[kellnerd]

While this is definitely useful for some languages and titles with enough different words, it is useless for languages that are unknown to the model and certain types of releases.

For such cases it is annyoing to remember changing the language before submission, so there should be a way to turn it off on the settings page. Maybe it should even be opt-in, what do people think?

[arsinclair]

I have figured out over time the language detection is not always accurate in Harmony, so I learnt to always check it when importing the release, so I guess I and other power users won't benefit much from it. But for the new users maybe it makes sense, it will reduce the number of errors.