Re: Review of std.signal

[Kagamin]

Also a similar warning for strongConnect: if you subscribe a big 
object (e.g. a complex UI form) to a signal and forget to 
unsubscribe, it will be retained with all the referenced data. In 
C# we register subscriptions in a supplementary container, so 
that when the form is disposed, it also disposes subscriptions in 
the container - it makes unsubscription easier if you don't 
forget to dispose the form.