DefaultHTTPErrorHandler is the default HTTP error handler.

ParseAcceptLanguageHeader reads the weighted header values like de-CH,de;q=0.9,en;q=0.8,en-US;q=0.7 into [{Lang:de-CH, Weight:1} {Lang:de Weight:0.9} {Lang:en Weight:0.8} {Lang:en-US Weight:0.7}].

SessionAuthToken create a request session if a valid API Key is found.