Adding browser's webp encoder (#72)

* Adding WebP (without feature detect in place)

* Adding WebP check

* Remove unused import

src/codecs/browser-webp/options.ts

@@ -0,0 +1,3 @@
+import qualityOption from '../generic/quality-option';
+
+export default qualityOption({ min: 0, max: 1, step: 0 });