v1.6.2

Update 1.6.2:

* Making Logger a singleton class, so there's no need to pass it through
  every single class, just class Logger::instance() whenever you want to
  use it. main() manages that pointer's destruction.
* Fixed bug while logging to file: Date didn't use to be shown.
* Fixed bug with translations: they didn't use to be applied, program
  used to run with default language even when user explicitly set it to
  Spanish.