* Clone() method in Localizer component allows to clone it just like LocalizationMiddleware does.
* RavenClientInterface contains all *raven.Client method, which allows external use without type casting.
* Tests and godoc fix for Go 1.15.
* all currencies supported in retailCRM"
* function which allows to pick currency symbol without interacting with map
* tweak for new function test
* check for undefined currency code
* increase timeout for failing test
* refactored test to WaitGroup, which resulted in finding and fixing actual data race in the job object
