Created new Add function whic allows pass directly low, high and object.

add.go

@@ -1,6 +1,15 @@
 package interval
 
-func (intvls *intervals) Add(itvl *Interval) error {
+func (intvls *intervals) Add(low, high int, obj interface{}) error {
+	itvl := &Interval{
+		Low:    low,
+		High:   high,
+		Object: obj,
+	}
+	return intvls.AddInterval(itvl)
+}
+
+func (intvls *intervals) AddInterval(itvl *Interval) error {
 	low := intvls.getInclusiveLow(itvl.Low)
 	high := intvls.getInclusiveHigh(itvl.High)