Add the possibility to scale sprites on X and Y

[muoji]

Currently it is only possible to scale a sprite globally, but looking at the code shows it is easy to add an option to have different values for the scale on X and Y.

A basic way of implementing this would be to replace the line 363 of quintus_sprites.js by:

if(p.scale) { this.matrix.scale(p.scale.x || p.scale || 1, p.scale.y || p.scale || 1);

[mpkorstanje]

That will break tweening animations that use scale.

It'd be better to add a scaleX, scaleY properties, and a setter scale(x,y) that scales both identically or independelty.

If p.scale is defined, we have to fall back to that to avoid breaking every bodies code.

[mpkorstanje]

Had a look at the code. Not a trivial amount of work if we want to keep things backwards compatible.

I reckon it is better to bit the bullet now.

[ghost]

@muoji if you want this change to be applied, make a pull request with all necesary changes as @mpkorstanje said. Don't forget to add some test runs to prove your enhancement. Thanks.