Ieee80211LayeredDecoder: removed SYMBOLS_PER_DATA_FIELD.
PPDU_SERVICE_FIELD_LENGTH -> PPDU_SERVICE_FIELD_BITS_LENGTH.
Removed an if condition based on SYMBOLS_PER_DATA_FIELD.
Ieee80211LayeredErrorModel: fixed a typo. Added printToStream().
Ieee80211LayeredReceiver: added default parameters.
LayeredAttenuation: set duration to analogModel->getDuration().
Ieee80211LayeredScalarRadioMedium: added module.
LayeredErrorModel: added printToStream().
LayeredReceiver: added some functions.
APSKModulationBase: added getEncodingTable().
ILayeredErroModel: inherits from IPrintableObject.
LayeredReceiver: added snirThreshold parameter and missing ifs.
Ieee80211LayeredErrorModel: implemented a simple symbol error model.