message: Update txbuild.js: make estimateTokenTransfer private
diff: @@ -441,6 +441,7 @@ function estimateAnnounce(messageHash: string,
  * just the recipient output (default = 1, if the token owner is also the bitcoin funder)
  * @returns {Promise} - a promise which resolves to the satoshi cost to
  * fund this token-transfer transaction
  + * @private
  */
  function estimateTokenTransfer(recipientAddress: string,
  tokenType: string,
  