* Add CA certificate in example

SHA1 fingerprint is broken now: more info: https://shattered.io

* Best error handling

When occur an error in WiFiClientSecure library just return the error message
and clean the context avoiding crash - fix for https://github.com/espressif/arduino-esp32/issues/211

Translate MbedTLS error codes in messages for best understanding

* Declarate certificates as const

mbedtls_pk_parse_key needs a const unsigned char * certificate. In old implementation the certificate was declarated as char * so first it converts to unsigned and after to const.

When we convert signed to unsigned it may result in a +1 larger output.

Fix issue https://github.com/espressif/arduino-esp32/issues/223

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

Implement semaphore and mutex to safeguard the ISR.
This is the proper way to handle hardware Interrupts with FreeRTOS. The
more regular approach may/will lead to exceptions

Use transactions to skip mutex locks for reads and writes

* Added LEDC Fade exmaple

* Renamed LEDCFade example to LEDCSoftwareFade

Added valueMax parameter for ledcAnalogWrite

* Remove usage of LED_BUILTIN constant to solve CI errors

* Refactoring EPS32NVS library to Preferences library

* Renaming all set* functions to put
* Added functions for float, double and bool

* Small redesign of Preferences API

* added type to put* function names
* for (u)int64_t used functions name with *(U)Long64
* added functions for long and unsigned long (same like int a unsigned int)

* Provide SSL/TLS functions to ESP32 with Arduino IDE

* Generate a new random number in case of reconnection

* Improved ESP32NVS default value support for read* functions

Fixed uninitialized NVS flash storage. Added example code.

* Add methods for String and remove unnecessary nvs_flash_init() in ESP32NVS class

+ other minor declaration fixes

* ESP32NVS function name renaming

* read* -> get*
* write* -> set*
* erase -> clear / remove

* 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 Touchread example

* Rename libraries/ESP32/examples/Touch/TouchRead.ino to libraries/ESP32/examples/Touch/TouchRead/TouchRead.ino

* Update TouchRead.ino

* 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