Added print methods to all chains (added to interface) so we can easily visualize the chains.
Added Rest implementations to Pitch, Volume, Duration, and Note classes. Rests are now generated in the spaces between notes in the MIDI file and are placed in their respective chains as default values (i.e. "R0" for pitch, and 0.00 for volume, and the length of their duration for the duration.
Added a condition to only add rests if they are present for an actual amount of time.