Firstly thanks to everyone for the code in github.com/esp8266/arduino
And I'm hoping that what I describe below will help everyone and make a better overall system...
Anyway... I downloaded the release from github today, but had lots of issues, with the compilor seeming to be missing a file and I also had upload isssues
I have created a better install package that doesn't require you to have a separate version of the Arduino IDE for ESP8266, in fact you can use the latest Arduino 1.6.2 rather than 1.6.1 which is on github.com/esp8266/arduino
(and which works
Basically, Arduino's third party hardware spec allows for new devices and their toolchains to be put in the "users" Arduino folder.
On Windows this is My Documents/Arduino
You need to create a hardware folder in the Arduino folder, then download and unzip my repo into the hardware folder, restart the Arduino IDE and select Generic ESP8266 from the boards menu and esptool from the programmer menu
This is all in my readme
If there was some way to cross link my repo just to the core code in github.com/esp8266/Arduino I would have done that, but as far as I'm aware, I can't add a sub project to my repo, which is a sub folder of another repo, and I a lot of the stuff on esp8266/arduino is not required at runtime