Keep an initial order of the currencies so they won't be in a different order after refreshing (#752)

This purely happend due to maps not keeping the order items are in. This way
it at least won't change throughout the runtime of wtfutil. Ideally it would
use and keep the order as specified by the user in the configuration but
right now there is no way to enforce this.

modules/exchangerates/widget.go

@@ -55,10 +55,11 @@ func (widget *Widget) content() (string, string, bool) {
 	if widget.err != nil {
 		out = widget.err.Error()
 	} else {
-		for base, rates := range widget.rates {
+		for base, rates := range widget.settings.rates {
 			out += fmt.Sprintf("[%s]Rates from %s[white]\n", widget.settings.common.Colors.Subheading, base)
 			idx := 0
-			for cur, rate := range rates {
+			for _, cur := range rates {
+				rate := widget.rates[base][cur]
 				out += fmt.Sprintf("[%s]%s - %f[white]\n", widget.CommonSettings().RowColor(idx), cur, rate)
 				idx++
 			}