Support custome object

Add support for serialization and deserialization of custom objects via Object.assign and Object.create
For example:

class A {
    a = 1
}
serialize(A, { classes: { A } })

get

const serialized = "(function(args) {var k = args[0].classes;return args[0].assign(Object.create(k.A.prototype), { a: 1 })})(arguments)"
function unserialize() {
    return eval(serialized)
}
unserialize({ classes: {A: function() {}}, assign: Object.assign })

Start with the issue's serialize(A, { classes: { A } }) example and compare the requested Object.assign/Object.create path with the package's current behavior. Done means custom objects can be serialized and deserialized while preserving the supplied class prototype and property data; add or run a round-trip test once the relevant entry point is located.