Merge pull request #6 from kodomazer/SoundGenerator

Sound generator
Update RandomChange.java
Update and rename RandomChange.java to Generator.java

ChangeTempo finished; changed Iterate to call void methods and just return initialMeasure in the end.
(Because the methods will one-by-one modify initialMeasure.)
Update Note.java

Added toShortMessage().
Merge pull request #8 from kodomazer/Tempo

Generator files