adds to display() method parameter PGraphics. This way we decouple all
subclasses of Displayable from PApplet, as well as allow to draw to
different framebuffers (PGraphics) upon our request. Which introduces a
great deal of flexibility into the architecture.
adds stub for ScoreDataManager a class responsible for
persisting/loading of the score data!
Intro has undergone a lot of changes:
-it is now decoupled from MatchIt sketch class
-it is now subclassing Displayable
-new constructor takes width/height/displayName parameters now
-it uses new version of Timer class, which is as well decoupled from
MatchIt sketch
-adds few comments
-implements display(PGraphics) method and introduces dependency on
PGraphics
-removes dependency on MatchIt.random() and moves it towards
Utils.random() 
-removes checkClick() method, as it didn't belong to the class and was
unncecessary.
adds few stub methods, which need to be implemented.