Unofficial Development Kit for Espressif ESP8266 v2.0.4

• Added official AT firmware from Espressif, directory "ESP8266_SDK\bin\at";
• Updated compiler xtensa-lx106-gcc and xtensa-lx106-g++
  
    Changed build option newlib, resulting in increased amount of free firmware IRAM.
  
    In the example "examples\nodemcu-firmware" on the old compiler Free IRam was 810 Byte, the new compiler Free IRam was 2986 bytes (disabled LUA_USE_BUILTIN_MATH)
• Update a utility "utils\esptool-ck.exe" to version 0.4.3;
• Update a utility "utils\esptool.exe";
• Updated library "libnet80211.a" and header file "user_interface.h" from Espressif SDK 1.0.1;
• Update RTOS SDK, directory "ESP8266_RTOS_SDK";
• Updated documentation:
  • Delete files:
    • ESP8266_IOT_Flash_read_write_guide_v0.2.pdf
    • ESP8266_IoT_SDK_Programming Guide_v1.0.1.pdf
  • Added files:
    • 2A-ESP8266__IOT_SDK_User_Manual__EN_v1.0.1.pdf
    • 2B-ESP8266__SDK__IOT_Demo__EN_v0.5.pdf
    • 2C-ESP8266__SDK__Programming Guide__EN_v1.0.1.pdf
    • 4A-ESP8266__AT Instrction Set__EN_v0.23.pdf
    • 4B-ESP8266__AT Command Examples__EN_v0.4.pdf
• Updated examples:
  • ESPWebFramework;
  • esp_mqtt;
  • nodemcu-firmware;
  • esphttpd;
  • ESP8266_Relay_Board;
  • esp8266_ili9341;
  • lwip_lib;