WiFiTelnetToSerial is also a test for hasClient().

Fixes: https://github.com/espressif/arduino-esp32/issues/373

This needs proper testing!
Fixes: https://github.com/espressif/arduino-esp32/issues/353

- call esp_wifi_start()
- separate tcp initialization to prepare for Ethernet
- setup dhcp addresses when using custom IP config for SoftAP

Thanks @miomir1981

* Add setNoDelay and getNoDelay to WiFiServer class

* Remote TCP disconnect not detected

Fixes: https://github.com/espressif/arduino-esp32/issues/329

Fixes: https://github.com/espressif/arduino-esp32/issues/304

Thanks @jliegner :)

thans @martinayotte

Should Fix: https://github.com/espressif/arduino-esp32/issues/234

Fixes: https://github.com/espressif/arduino-esp32/issues/275

Fixes: https://github.com/espressif/arduino-esp32/issues/263

Actually WiFiMulti is not working due some functions haven't equal comportment of ESP8266
Replace status == WL_DISCONNECTED => status != WL_CONNECTED
Replace scanComplete() => scanNetworks()

Maybe is more interesting, for keep the maximum compatibility, investigate why WL_DISCONNECTED and scanComplete() doesn't works in this case instead of just replace by this pull request.

fixes: https://github.com/espressif/arduino-esp32/issues/119

* Rework WiFiClient

Rework WiFiClient to correct error where making a copy of a WiFiClient object resulted in the socket being closed prematurely.

Added loop and select to write to handle/prevent EAGAIN errors.

* Rework WiFiClient to use shared_ptr

Rework changes to utilize shared_ptr rather than manually maintaining reference count. 

Revert changes to write

* Incorporate comments from review

Move WiFiClientSocketHandle and fd() into WiFiClient.cpp

The send call may return EAGAIN. This indicates a recoverable error and a retry should be attempted. The current implementation treats this as a fatal error. Further, the current implementation strips the error code, setting it to 0, which prevents the caller from handling it directly. 
This change utilizes select to verify the socket is available prior to calling send and will retry on an EAGAIN condition.

WiFi and BlueTooth can now be started and stopped at will.
basic functions added to esp32-hal to start and stop the BT radio
SimpleBLE class added to show the most basic functionality
Example to show how to switch between BT, WiFi or Both

* Add new partition scheme

* Init NVS early, so it can be used without BT or WiFi

fixes: https://github.com/espressif/arduino-esp32/issues/191

Fixes: https://github.com/espressif/arduino-esp32/issues/173

Currently there is bug in WiFiUDP library when you want to use beginPacket(...) without listening on socket (without calling begin(...) first). You can't send any data because socket is not open and also tx_buffer is not allocated which cause crash while writing data to tx_buffer.

* Add build time partitions compilation

* Fix wrong definition of SS pin

* Add support for core debug level selection

* update idf libs

* Added a basic WiFi UDP client example: a sketch that sends random bytes over udp.

* Updated udp example and included Python and Ruby UDP servers.

fixes: https://github.com/espressif/arduino-esp32/issues/143

fixes: https://github.com/espressif/arduino-esp32/issues/144

* smartConfig support

* fixed bug, added example

* added _smartConfigDone = ture

* changed example name, added explanation

Change return value of UDP::endPacket() to match specifications

Ref: https://github.com/espressif/arduino-esp32/issues/138

need close(sockfd) before sockfd = -1, "_connected = false and close socket" means stop() function. (#73)