Added ability to translate info widgets

Now it shows infoWidgets in currentDetected language. If translation is
missing english is used.
Added other languages to po files

Translation are created based on Previous Language.js files
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
Updated translations
Updated version of i18next from 1.7.2 to 1.7.3
English translation works now
Updated some translation with strings from old lang.js translation
Make some translator comments more descriptive
Fixes Catalan translation encoding problems
Moved localized direction strings outside of function

So that they are only translated once, not every time function is
called.
Added new Translator comments to modes of transport
Update Localization README

Added info about language.js file and date/time formats
Merge branch 'po_localization' into slo_loc_timeformat

Conflicts:
	otp-leaflet-client/src/main/webapp/index.html
	otp-leaflet-client/src/main/webapp/js/otp/config.js
	otp-leaflet-client/src/main/webapp/js/otp/locale/German.js
	otp-leaflet-client/src/main/webapp/js/otp/locale/Slovenian.js
Changed time/date format to new type
Updated English.js
Removed unecessary time/date strings in locale files