This change reorganises the Wi-Fi MAC high classes in attempt to
reduce duplication of functionality that is required for more than one
of the MAC high models. A new class called RegularWifiMac has been
created. This derives from the abstract WifiMac, and is parent of
AdhocWifiMac, StaWifiMac, ApWifiMac, and MeshWifiInterfaceMac. The QoS
and non-QoS class variants are no longer, with a RegularWifiMac
attribute "QosSupported" allowing selection between these two modes of
operation. QosWifiMacHelper and NqosWifiMacHelper continue to work as
previously.
Updates to some regression traces are necessary because the
reorganisation has led to random number streams being initialised in
slightly different orders and thus over-the-air timing changing.
