Application must now manually call application.Draw in all cases

This behavior is way more consistent, and it makes the drawing code
a bit simpler.

examples/hello/main.go

@@ -33,14 +33,12 @@ func main () {
 	if err != nil { panic(err) }
 	
 	redraw()
-	application.Draw()
 	go tick()
 
 	for {
 		select {
 		case <- tickPing:
 			redraw()
-			application.Draw()
 		
 		case event := <- channel:
 			switch event.(type) {
@@ -72,6 +70,8 @@ func redraw () {
 	application.SetRune(5, 1, ':')
 	application.SetRune(6, 1, rune(second / 10 + 48))
 	application.SetRune(7, 1, rune(second % 10 + 48))
+	
+	application.Draw()
 }
 
 func tick () {