Enchanged FunctionAverage class, new RandomArt constructor

-now objects in the array of FunctionAverage dont necesserely have the
same amount of nested levels
-now FunctionAverage could have more than 2 objects where the avg is
calculated
-new constructor to RandomArt where user can determine the amount of
nested levels to different colors (r,g,b) to see the effect of
different amount of nested levels.