- Better inheriting of `clone` + `copy` methods where appropriate. This is done by calling `new this.constructor()` in parent classes. `this.constructor` refers to the current instance's constructor, so it should all compose nicely;

- Pass in attributes directly as arguments to constructor when cloning, where appropriate (if arguments pattern is different from parent class). This mean `copy` isn't relied on to set those attributes.

- Change order of `clone` in some files (for better visibility into its relationship with `copy`, and to maintain consistency; can return to previous order if necessary);

- Fix CubeTexture's clone method