Fix comments according to best practices by effective go (#219)

exchanges/bitflyer/bitflyer.go

@@ -407,7 +407,7 @@ func (b *Bitflyer) GetFee(feeBuilder exchange.FeeBuilder) (float64, error) {
 	return fee, nil
 }
 
-// getDepositFee returns fee when performing a trade
+// calculateTradingFee returns fee when performing a trade
 func calculateTradingFee(purchasePrice float64, amount float64) float64 {
 	fee := 0.0015
 	// bitflyer has fee tiers, but does not disclose them via API, so the largest has to be assumed

exchanges/bithumb/bithumb.go

@@ -592,7 +592,7 @@ func (b *Bithumb) GetFee(feeBuilder exchange.FeeBuilder) (float64, error) {
 	return fee, nil
 }
 
-// getDepositFee returns fee when performing a trade
+// calculateTradingFee returns fee when performing a trade
 func calculateTradingFee(purchasePrice float64, amount float64) float64 {
 	fee := 0.0015
 

exchanges/nonce/nonce.go

@@ -45,7 +45,7 @@ func (n *Nonce) Set(val int64) {
 	n.mtx.Unlock()
 }
 
-// Returns a string version of the nonce
+// String returns a string version of the nonce
 func (n *Nonce) String() string {
 	n.mtx.Lock()
 	result := strconv.FormatInt(n.n, 10)

exchanges/yobit/yobit.go

@@ -423,7 +423,7 @@ func getInternationalBankWithdrawalFee(currency string, amount float64, bankTran
 	return fee
 }
 
-// No real fees for yobit deposits, but want to be explicit on what each payment type supports
+// getInternationalBankDepositFee; No real fees for yobit deposits, but want to be explicit on what each payment type supports
 func getInternationalBankDepositFee(currency string, amount float64, bankTransactionType exchange.InternationalBankTransactionType) float64 {
 	var fee float64
 	switch bankTransactionType {