Issue 18: Some elementary sound generator is needed for the initial release
Project Member Reported by fuka2@fuxoft.cz, May 21, 2010
Implement function dynawa.sound.alert(time[int], tone[int]) where "time" is 
sound duration in ms and "tone" is sound type (frequency). The sound should 
not be just a simple sine wave or square wave but something more prominent 
and identifiable. Consult with me.

If dynawa.sound.alert() is called again during the sound generation, the 
previous sound immediately stops and new one is started.