Add some simple functions for Swift bindings (iOS)

src/yggdrasil/adapter.go

@@ -1,17 +1,8 @@
 package yggdrasil
 
-// Defines the minimum required functions for an adapter type.
-type AdapterInterface interface {
-	init(core *Core, send chan<- []byte, recv <-chan []byte)
-	read() error
-	write() error
-	close() error
-}
-
 // Defines the minimum required struct members for an adapter type (this is
 // now the base type for tunAdapter in tun.go)
 type Adapter struct {
-	AdapterInterface
 	core *Core
 	send chan<- []byte
 	recv <-chan []byte