blend-transforms breaks visibility inheritance

[diarmidmackenzie]

Object X blends transforms of A & B.

Object is parented in the DOM by parent C. C could be A, B or something entirely other.

Set C to visible = false. Expectation is (or at least, might be), that X becomes invisible, as it's parent has been set to invisible. But because X is not a child of C in the THREE.js Object3D hierarchy, this doesn't happen - X remains visible.

Would be useful to have the option to set things up so that X inherits visibility status from C. This should allow for the fact that the actual visibility state of C might either be set on C, or on some ancestor of C.