Fix serialization of the EtherLink object

Fix serialization of the EtherLink object

dev/etherlink.cc:
    - The EtherLink::Link object is no lonver serializable, so it is now
    necessary to prepend the object's name (as determined by the parent)
    to all parameters.
    - Fix the serialization of the LinkDelayEvent so it actually works
    - Rename some variables to make serialization simpler
dev/etherlink.hh:
    - Make the EtherLink::Link object *not* derive from serializeable.
    Instead, the serialize function will take a base name from
    the parent EtherLink object and prepend that base name to each of
    its variable names when serializing.  This is similar to the
    PacketData and PacketFifo classes.
    - Make the EtherLink::Link object keep a pointer to its parent and its
    link number so the LinkDelayEvent can be properly serialized.
    - Rename some variables to make serialization simpler.

--HG--
extra : convert_revision : e5aa54cd9e07b5e033989809100e1640abfb8bed