inner class/enum should be static

Author: KengoTODA

src/main/java/difflib/Delta.java

@@ -35,7 +35,7 @@ public abstract class Delta<T> {
      * Specifies the type of the delta.
      *
      */
-    public enum TYPE {
+    public static enum TYPE {
     	/** A change in the original. */
         CHANGE, 
         /** A delete from the original. */

src/main/java/difflib/DiffRow.java

@@ -40,7 +40,7 @@ public DiffRow(@Nonnull Tag tag, @Nullable String oldLine, @Nullable String newL
         this.newLine = newLine;
     }
 
-    public enum Tag {
+    public static enum Tag {
         INSERT, DELETE, CHANGE, EQUAL
     }