code: function Drop(rainyday, centerX, centerY, min, base) {
      this.x = Math.floor(centerX);
      this.y = Math.floor(centerY);
      this.r = (Math.random() * base) + min;
      this.rainyday = rainyday;
      this.context = rainyday.context;
      this.reflection = rainyday.reflected;
  }
docs: Defines a new raindrop object.
  @param rainyday reference to the parent object
  @param centerX x position of the center of this drop
  @param centerY y position of the center of this drop
  @param min minimum size of a drop
  @param base base value for randomizing drop size