This change adapts pion/ice to use a new interface for most network
related operations. The interface was formerly a simple struct vnet.Net
which was originally intended to facilicate testing. By replacing it
with an interface we have greater flexibility and allow users to hook
into the networking stack by providing their own implementation of
the interface.
Timeout check must be inside the scope of routine leak check.
Routine leak check internally has wait for routine exit which
may causes timeout error in some case.
