Ieee80211LayeredDecoder: defines moved inside the namespaces.
Ieee802011LayeredEncoder: added some helper functions, added channelSpacing parameter.
Ieee80211LayeredErrorModel: factored some code out.
Ieee80211LayeredReceiver: ***
Ieee80211LayeredTransmitter: fixed a FIXME, check_and_cast -> dynamic_cast. bitrate depends on controlInfo or picks a default value.
APSKModulationBase: added a reference URL.
Ieee80211OFDMModulator: added a FIXME.
LayeredEncoder: added a missing if.
LayeredTransmitter: added bitrate parameter.
Examples: added a Ieee80211 example that uses the layered architecture.