Reorder items in generated source files.

Ideally they would always have been sorted as such, but this seems more
critical in migrating from one service definition to another where the ordering might
change.

scpd/scpd.go

@@ -2,6 +2,7 @@ package scpd
 
 import (
 	"encoding/xml"
+	"sort"
 	"strings"
 )
 
@@ -37,6 +38,14 @@ func (scpd *SCPD) Clean() {
 	}
 }
 
+func (scpd *SCPD) OrderedActions() []Action {
+	actions := append([]Action{}, scpd.Actions...)
+	sort.SliceStable(actions, func(i, j int) bool {
+		return actions[i].Name < actions[j].Name
+	})
+	return actions
+}
+
 func (scpd *SCPD) GetStateVariable(variable string) *StateVariable {
 	for i := range scpd.StateVariables {
 		v := &scpd.StateVariables[i]