Use certmagic, simplify config, set HTTP timeouts and a modern TLSConfig

vendor/github.com/xenolf/lego/registration/user.go

@@ -0,0 +1,13 @@
+package registration
+
+import (
+	"crypto"
+)
+
+// User interface is to be implemented by users of this library.
+// It is used by the client type to get user specific information.
+type User interface {
+	GetEmail() string
+	GetRegistration() *Resource
+	GetPrivateKey() crypto.PrivateKey
+}