esp32: esp-touch supports both multicast and broadcast packets

esp32: esp-touch supports both multicast and broadcast packets

    Previously, esp-touch only supports multicast packets which are
    transmitted from cellphone. But for most dual frequency routers
    whose SSIDs of 5G and 2.4G are the same, broadcast packets are
    forwarded from 5G interface to 2.4G interface while multicast
    packets are not. In order to make esp-touch work when cellphone
    connects to 5G interface of these routers, esp-touch is improved
    to support both multicast and broadcast packets. Meanwhile, new
    APP which is compiled with Andriod or IOS library(>= v0.3.6.2)
    must be used in this situation. Note that for some routers,
    broadcast and multicast packets are forwarded from 5G interface
    to 2.4G interface only when another WiFi device is connected to
    2.4G interface of the router. Old APP which is compiled with
    Android or IOS library(< v0.3.6.2) also works with this improvement
    when cellphone connects to 2.4G interface of the router.

    The Android and IOS library of new esp-touch APP is now available
    on Github.
    Android: https://github.com/EspressifApp/EsptouchForAndroid
    IOS: https://github.com/EspressifApp/EsptouchForIOS