esp-idf v4 not supported

[JoshuaRack]

Sorry I didn't keep the logs, so this won't be very specific.
When building the smart light example against a relatively recent pull of the ESP-IDF master branch,
I got link errors complaining about lwip_recvfrom_r. It turns out newer versions of ESP-IDF use a newer version of lwip in which the sockets api has been changed and this has been removed.
Building with ESP_IDF release/v3.3 worked fine.
It would be useful to document the supported ESP-IDF version in the quickstart guide. And/or check which idf version is being used and modify the calls to support the the newer version.
Thanks,

[cpq]

mDash library is in sync with the esp32 Arduino core
That one is on IDF 3 at this moment, so mDash also is.