currency: Make pairs.Add variadic (#1566)

* Making Pairs(Add) Variatic

* Slight improvements

* Implementation overhaul

* Improvements

* Changing code which can use the variadic functionality

* Fixing silliness

* thing left over

exchanges/sharedtestvalues/sharedtestvalues.go

@@ -168,10 +168,8 @@ func SetupCurrencyPairsForExchangeAsset(t *testing.T, exch exchange.IBotExchange
 		t.Fatal(err)
 	}
 	epLen := len(enabledPairs)
-	for i := range cp {
-		availPairs = availPairs.Add(cp[i])
-		enabledPairs = enabledPairs.Add(cp[i])
-	}
+	availPairs = availPairs.Add(cp...)
+	enabledPairs = enabledPairs.Add(cp...)
 	if len(availPairs) != apLen {
 		err = b.CurrencyPairs.StorePairs(a, availPairs, false)
 		if err != nil {

exchanges/subscription/subscription.go

@@ -159,8 +159,6 @@ func (s *Subscription) AddPairs(pairs ...currency.Pair) {
 		return
 	}
 	s.m.Lock()
-	for _, p := range pairs {
-		s.Pairs = s.Pairs.Add(p)
-	}
+	s.Pairs = s.Pairs.Add(pairs...)
 	s.m.Unlock()
 }