Make portions of ListChanges public

This enables other callers to use ListChanges, for example a plugin
might want to drive ListChanges with their own arguments without going
through the args4j option parser.

Change-Id: I5cfd342673e9e381079b2c1891fe73e48be3e93b

gerrit-common/src/main/java/com/google/gerrit/common/changes/ListChangesOption.java

@@ -38,6 +38,14 @@ public enum ListChangesOption {
     this.value = v;
   }
 
+  public int getValue() {
+    return value;
+  }
+
+  public static ListChangesOption fromValue(int value) {
+    return ListChangesOption.values()[value];
+  }
+
   public static EnumSet<ListChangesOption> fromBits(int v) {
     EnumSet<ListChangesOption> r = EnumSet.noneOf(ListChangesOption.class);
     for (ListChangesOption o : ListChangesOption.values()) {