Use satoshisBN internally

.jshintrc

@@ -28,7 +28,7 @@
     "maxcomplexity": 6,   // Cyclomatic complexity (http://en.wikipedia.org/wiki/Cyclomatic_complexity)
     "maxdepth": 4,        // Maximum depth of nested control structures
     "maxlen": 120,        // Maximum number of cols in a line
-    "multistr": true      // Allow use of multiline EOL escaping
+    "multistr": true,     // Allow use of multiline EOL escaping
 
     "predef": [ // Extra globals.
         "after",

lib/transaction/transaction.js

@@ -666,7 +666,7 @@ Transaction.prototype.verify = function() {
   var valueoutbn = BN(0);
   for (var i = 0; i < this.outputs.length; i++) {
     var txout = this.outputs[i];
-    var valuebn = txout._satoshis;
+    var valuebn = txout._satoshisBN;
     if (valuebn.lt(0)) {
       return 'transaction txout ' + i + ' negative';
     }