Add tones, including a launch countdown sequence.

lib/launch_rocket.ks

@@ -1,6 +1,7 @@
 RunOncePath("lib/throttle").
 RunOncePath("lib/navigation").
 RunOncePath("lib/navball").
+RunOncePath("lib/sound").
 
 // Calculate the direction to lock during ascent.
 function getClampedDir {
@@ -43,9 +44,10 @@ function Launch {
 
   // Countdowns are cute.
   print "Initiating automated launch sequence.".
+  PlayCountdown().
   from { local x is 5. } until x = 0 step { set x to x - 1. } do {
     print "..." + x.
-    wait 0.5.
+    wait 1.0.
   }
 
   // staging logic. Stage as many times as needed until we finish ascent.