fix: Pubkey(point) and Privkey(bn)

lib/privkey.js

@@ -6,7 +6,7 @@ var Random = require('./random');
 
 var Privkey = function Privkey(bn) {
   if (!(this instanceof Privkey))
-    return new Privkey(obj);
+    return new Privkey(bn);
   if (bn instanceof BN)
     this.bn = bn;
   else if (bn) {

lib/pubkey.js

@@ -4,7 +4,7 @@ var privkey = require('./privkey');
 
 var Pubkey = function Pubkey(point) {
   if (!(this instanceof Pubkey))
-    return new Pubkey(obj);
+    return new Pubkey(point);
   if (point instanceof Point)
     this.point = point;
   else if (point) {