Add support for STM32, add SSLClient integration to add SSL for Ethernet (now GMail is supported), minor fix

Add STM32 support.
Add SPI Flash.
Add SSLClient integration to allow sending Emails with SSL encryption (like Gmail) with ethernet (tested with STM32, ESP32, w5500, and enc28j60).
Fix the memory leak if all send goes wrong. minor fix

EMailSender fix multiple emails send

EMailSender fix multiple emails send with the same Wifi Client.

Add some ESP32 examples with the new filesystem support

Add some ESP32 examples with the new filesystem support

Enhance support for ESP32

Enhance support for ESP32 with all file system (LITTLEFS and FFat) and fix the new management of certificates in the ESP32 Arduino core > 1.0.4.

EMailSender add support for LittleFS

In this version we add support for LittleFS the future standard filesystem for esp8266.

EMailSender support for Arduino SAMD (WiFiNINA) boards

Thanks to Arduino foundation that support the develop, now support for Arduino SAMD (WiFiNINA) boards (Arduino UNO WiFi Rev.2, Arduino NANO 33 IoT, Arduino MKR 1010 and Arduino MKR VIDOR 4000 WiFi etc.)

EMailSender additional features for postfix SMTP server

Add possibility to use EHLO instead of HELO, and SASL login.

EMailSender more array types for distribution list

Now you can use char** String[] and const char** to manage distribution list array.

EMailSender name of email from

Add little features, add user name on from label (#9) and minor fix.

EMailSender with distribution list

Version 2 of the EMailSender library, a big evolution respect to version 1, with support for Arduino with w5100, w5200 and w5500 ethernet shield and enc28J60 clone devices, and support for esp32 and esp8266.
Now you can add attachments also, loaded from storage device like SD or SPIFFS.

Fix the escape character to support Outlook.
Add new distribution list features.