Giving access to `Task` can be done within the cur...

# tornadofx

[edvin]

Giving access to Task can be done within the current structure, but it would mean that this is Task<*>. If you try to access valueProperty, it would be Any instead of T. To solve that, I think runAsync would need to take a type parameter, and that sucks. Nobody wants to write runAsync<Customer> { loadCustomer() }.