Add check if webp images are supported

[vforsh]

Please add the check for webp image format. It becomes more and more popular. Something like game.device.webp will be great.

For example, this is how Modernizr performs such check - https://github.com/Modernizr/Modernizr/blob/master/feature-detects/img/webp.js

[samme]

There would be a small time cost to loading the image.

The implementation would also be a little challenging because none of Phaser.Device's tests are asynchronous, like this one.

[ankush-badyal]

Does Phaser-ce support webp or other latest image formats?

[samme]

That would depend on the browser's support for WebP.

[oktayacikalin]

I think it would make sense to have an automatism in the atlas loader, which would either load the webp or other format.