Release of v8.0

Калькулятор бюджета. Мажорный релиз. Add the page with currency exchange rates that is automatically updated on a daily basis.

Change Log:

• add the page with currency exchange rates:
  • use the ExchangeRate-API service for getting currency exchange rates:
    • store an ExchangeRate-API key in the settings
    • store the list of currencies to be monitored in the settings
  • update currency exchange rates:
    • manually
    • automatically on a daily basis (optionally):
      • display a notification of such an update (optionally)
    • make currencies unique by timestamp and code
  • displaying:
    • support the wide list of currencies to display (principle of selecting and displaying available currencies):
      • selection:
        • support all currencies whose symbols are included in the Font Awesome library version 4.2.0
        • if one symbol corresponds to several currencies, support those currencies that are included in the list of "Most traded currencies" for 2022
      • displaying:
        • if a unique symbol is found for a currency, use it
        • if a special prefix is available for a currency with a non-unique symbol (see the "World Bank Editorial Style Guide 2020" document, appendix D), use it
        • otherwise use the ISO 4217 alphabetic code as the prefix
        • for all other currencies for which no symbol is found, just use the ISO 4217 alphabetic code
      • add the tenge symbol separately as an SVG image (since it is not in the Font Awesome library version 4.2.0)
    • support the several modes of displaying currency exchange rates:
      • supported modes of displaying:
        • all
        • last by day
        • last at all
      • store a mode of displaying in the settings
    • separate actual and not actual currencies (the last ones at all are considered actual)
  • support currency exchange rates in backups
• misc.:
  • use a background thread in the MainActivity.callGuiFunction() method
  • update the project via the Android Studio