Choosing a language also chooses datepicker localization and metric

Removed unused settings from locale files
Now default language is always English. And correct language is set
automatically with i18next language detection.
Metric usage is also set based on Locale used
Refactored language settings

Language name and code are now in Language.js itself
Language code is still in 2 places.
Added Catalan and Italian preliminary translation
Updated French name
InfoWidgets are now read from locale

If they don't exist english ones are used