This is an Editor, C++ Compiler and ESPTool Uploader to put machine code onto various types of chip. It now caters for ESP8266 with the libraries which have been especially adapted for us.
This IDE has many libraries for the ESP8266 and many from the Arduino boards that can be adapted to suit the WiFi chip.
Get the IDE here, unzip, Linux-click on ./Arduino script http://www.arduino.cc/en/Main/Software
Get the ESP8266 libraries here and follow readme instructions https://github.com/esp8266/Arduino