Wi-Fi callback mechanism
Improving the previous "decay model" for the Wi-Fi model to follow what appears in the paper "A Flow-Level Wi-Fi Model for Large Scale Network Simulation".
It is done using the nonlinear callback feature to adapt the capacity of a Wi-Fi link depending on the number of concurrent flows on the link.
Calibration values can be changed to match different MCS configurations (existing are working for 802.11n 5GHz with MCS 3).
The implementation requires adding the callback capacity to Wi-Fi links (WIFI sharing policy).
An example matching the description of the model is provided in teshsuite/models/wifi_usage_decay/wifi_usage_decay.cpp