add reverse sort order option, toggle

sort.go

@@ -30,6 +30,9 @@ func (a Containers) Len() int      { return len(a) }
 func (a Containers) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
 func (a Containers) Less(i, j int) bool {
 	f := Sorters[GlobalConfig["sortField"]]
+	if GlobalConfig["sortReversed"] == "1" {
+		return f(a[j], a[i])
+	}
 	return f(a[i], a[j])
 }