breaking pointer mess

- ExternalPointer (?)
- nip27, nip22 and nip10 functions to return pointers
- get rid of sdk/thread helpers that were just a thin layer over nip10 and nip22

nip19/pointer.go

@@ -9,8 +9,13 @@ import (
 func EncodePointer(pointer nostr.Pointer) string {
 	switch v := pointer.(type) {
 	case nostr.ProfilePointer:
-		res, _ := EncodeProfile(v.PublicKey, v.Relays)
-		return res
+		if v.Relays == nil {
+			res, _ := EncodePublicKey(v.PublicKey)
+			return res
+		} else {
+			res, _ := EncodeProfile(v.PublicKey, v.Relays)
+			return res
+		}
 	case nostr.EventPointer:
 		res, _ := EncodeEvent(v.ID, v.Relays, v.Author)
 		return res