v3.0.0

- Remove default API key; you will now need to provide your own OpenWeatherMap API key for the app to work (#376 by @triallax)
- Start work on internationalization support; hopefully you will become able to translate Clima to your language(s) in the near future! (#376 by @triallax)
- Make various other small UI, UX, and internal improvements (by @triallax)