mobility settings were moved to ConstantMobilityNodeContainer class
MAC and PHY preparations were moved to WifiNodeContainer class
getNetDeviceContainer and getDevice in ConstantMobilityNodeContainer
SetReceiveOkCallback on YansWifiPhy
difs-wifi-mac uses companion classes
SetReceiveErrorCallback for YasnWifiPhy
reformatting
separating IPv4 related features to Ipv4NodeContainer class
factorial is a sample of tail recursion
IPv4 related methods were moved to Ipv4NodeContainer class
fixed signed and unsigned mismatches
scheduleSendPacket accepts destination node
some assertions were inserted