clean code and add testcases

enzevalos_iphone/SwiftPGP.swift

enzevalos_iphoneTests/AutocryptTest.swift

enzevalos_iphoneTests/CryptoTests.swift

enzevalos_iphoneTests/MailServerConfigurationTest.swift

enzevalos_iphoneTests/MailTest.swift

...oneTests/testKeys/Alice Letterbox (439EE43C) – Public.asc

...phoneTests/testKeys/AliceMultiIDs (439EE43C) – Public.asc

...phoneTests/testKeys/Bob Letterbox (0B6CD0A0) – Secret.asc

enzevalos_iphoneTests/testMails/multiIDs.eml

enzevalos_iphoneTests/testMails/multiIDs2.eml

enzevalos_iphoneTests/testMails/signedEncMailFromApple.eml

enzevalos_iphoneUITests/OnboardingTest.swift