Corrected code for Inheritance which was not implementing inheritance using extends keyword

[ShenpaiSharma]

Fixes #921

Changes:
Changes Inheritance code such that both the classes SpinArms and SpinSpots extend the Spin class. As initially in Inheritance, two separate classes are defined, which are defining their own spin classes and not using extends keyword.

Changed code:

let spots, arm;

function setup() {
  createCanvas(640, 360);
  arm = new SpinArm(width/2, height/2, 0.01);
  spots = new SpinSpots(width/2, height/2, -0.02, 90.0);
}

function draw() {
  background(204);
  arm.update();
  arm.display();
  spots.update();
  spots.display();
}

class Spin {
  constructor(x,y,s) {
    this.x = x;
    this.y = y;
    this.speed = s;
    this.angle = 0.0;
  }
  
  update() {
    this.angle += this.speed;
  }
}

class SpinArm extends Spin {
  constructor(x, y, s) {
    super(x,y,s)
  }

  display() {
    strokeWeight(1);
    stroke(0);
    push();
    translate(this.x, this.y);
    this.angle += this.speed;
    rotate(this.angle);
    line(0, 0, 165, 0);
    pop();
  }
}

class SpinSpots extends Spin {
  constructor(x, y, s, d) {
    super(x,y,s)
    this.dim = d;
  }

  display() {
    noStroke();
    push();
    translate(this.x, this.y);
    this.angle += this.speed;
    rotate(this.angle);
    ellipse(-this.dim/2, 0, this.dim, this.dim);
    ellipse(this.dim/2, 0, this.dim, this.dim);
    pop();
  }
}

Screenshots of the change:

Intially:

After change:

[ShenpaiSharma]

Hi, @limzykenneth , can you please review my PR?

[limzykenneth]

There's some formatting changes required. Once those are fixed we can merge. Thanks!

[limzykenneth]

There's an extra white space here. It would help if you set your text editor to automatically trim trailing whitespaces.

[ShenpaiSharma]

OK, I will take care of that. Thanks!!

[limzykenneth]

The white space is not yet removed.

[ShenpaiSharma]

Ohh, sorry, I thought of something different.

[limzykenneth]

Looks good. Thanks!