EdDSA: Make more classes serializable (Github PR #68)

core/java/src/net/i2p/crypto/eddsa/math/Encoding.java

@@ -1,5 +1,7 @@
 package net.i2p.crypto.eddsa.math;
 
+import java.io.Serializable;
+
 /**
  * Common interface for all (b-1)-bit encodings of elements
  * of EdDSA finite fields.
@@ -8,7 +10,7 @@ package net.i2p.crypto.eddsa.math;
  * @author str4d
  *
  */
-public abstract class Encoding {
+public abstract class Encoding implements Serializable {
     protected Field f;
 
     public synchronized void setField(Field f) {

core/java/src/net/i2p/crypto/eddsa/math/ScalarOps.java

@@ -1,11 +1,13 @@
 package net.i2p.crypto.eddsa.math;
 
+import java.io.Serializable;
+
 /**
  *
  * @since 0.9.15
  *
  */
-public interface ScalarOps {
+public interface ScalarOps extends Serializable {
     /**
      * Reduce the given scalar mod l.
      * <p>