Swift 5 support

[andreadelfante]

Hi,
love this lib. Can you provide the support for Swift 5?

[b-onc]

@MP0w Is this library abandoned?

[MP0w]

A big part of it is not needed anymore because of swift’s Codable, we could push a breaking change version that removes Serializable and updates the rest to swift 5

[dynaheirbe]

A breaking change would be fine by me... please do so!