feat(sprites): create sprites using sharp

[blacha]

• feat(sprites): use sharp + mapbox to convert svg's into a sprite sheet
• feat(sprites): add cli
• feat(sprites): add example sprites
• feat: upgrade sharp to 0.30.x
• feat: optimise output file size

[Wentao-Kuang]

We can just define the class variables above like private ratio:CommandIntegerListParameter and define them in onDefineParameters(): function.

[blacha]

nope, because then they are undefined since they are not defined in the constructor. I think its a strict null check setting setting in typescript

class Foo {
  x: number;
  y: number;
  constructor(){ 
    this.x = 1;
  }
  doSomething() {
   this.x // number
   this.y // number | undefined
  }

[Wentao-Kuang]

Cool, that's why we always checking defined before using them.

[blacha]

https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-7.html#strict-class-initialization