message: Fixed comment over `TxBuilder.balance`
  Original comment for `Positive` case is wrong ("more outputs+fees than inputs"), and also a bit hard to read the logic. Tried to make it as obvious as possible.
diff: @@ -211,8 +211,8 @@ impl TxBuilder {
  /// Try to return the differential between the outputs (including fees) and the inputs
  /// * Zero: we have a balanced transaction where inputs === outputs
  - /// * Negative: more inputs money is needed, sum of output and fees is greater than sum of inputs
  - /// * Positive: more outputs+fees than inputs, leading to more money associated to fees.
  + /// * Negative: (outputs+fees) > inputs. More inputs required.
  + /// * Positive: inputs > (outputs+fees). Excessive input goes to larger fee.
  pub fn balance<'a, F: FeeAlgorithm>(&self, f: &'a F) -> Result<CoinDiff> {
  let fee = self.calculate_fee(f)?;
  let inputs = self.get_input_total()?;
  