improvements, start integration tests

improved various funcs, removed extraneous things (e.g. Item.Attrs).

first integration test. more will come.

collection_funcs.go

@@ -7,8 +7,6 @@ import (
 	`github.com/godbus/dbus/v5`
 )
 
-// TODO: add method Relabel
-
 /*
 	NewCollection returns a pointer to a Collection based on a Service and a Dbus path.
 	You will almost always want to use Service.GetCollection instead.
@@ -188,6 +186,18 @@ func (c *Collection) Label() (label string, err error) {
 	return
 }
 
+// Relabel modifies the Collection's label in Dbus.
+func (c *Collection) Relabel(newLabel string) (err error) {
+
+	var variant dbus.Variant = dbus.MakeVariant(newLabel)
+
+	if err = c.Dbus.SetProperty(DbusItemLabel, variant); err != nil {
+		return
+	}
+
+	return
+}
+
 // Created returns the time.Time of when a Collection was created.
 func (c *Collection) Created() (created time.Time, err error) {