BufferWriter().toBuffer convenience method

It does the same thing as .concat(), but may be easier to remember, since the
rest of the library uses the ".toBuffer()" convention

lib/bufferwriter.js

@@ -14,6 +14,10 @@ BufferWriter.prototype.set = function(obj) {
   return this;
 };
 
+BufferWriter.prototype.toBuffer = function() {
+  return this.concat();
+};
+
 BufferWriter.prototype.concat = function() {
   return Buffer.concat(this.bufs);
 };

test/bufferwriter.js

@@ -22,6 +22,17 @@ describe('BufferWriter', function() {
 
   });
 
+  describe('#toBuffer', function() {
+    
+    it('should concat these two bufs', function() {
+      var buf1 = new Buffer([0]);
+      var buf2 = new Buffer([1]);
+      var bw = new BufferWriter({bufs: [buf1, buf2]});
+      bw.toBuffer().toString('hex').should.equal('0001');
+    });
+
+  });
+
   describe('#concat', function() {
     
     it('should concat these two bufs', function() {