A Swift Encoder that serializes keyed values in a format similar to logfmt.

Example:

import LogfmtEncoder

struct MyLogMessage: Encodable {
    var foo: String
    var bar: Int
    var baz: URL
}

let message = MyLogMessage(foo: "My string", bar: 42, baz: URL(string: "http://example.com/")!)
try TextEncoder().encoder(message)
// => foo="My string" bar=42 baz="http://example.com/"

• Unkeyed containers are not supported, since they don't map well to key identifiers for the log format. If you try to encode a value that asks for an unkeyed container, a fatalError() will be triggered.
• A top-level single value is not supported. logfmt messages must have keys.