add eclipse howto

doc/eclipse/eclipse.md

@@ -0,0 +1,34 @@
+using Eclipse with Arduino ESP8266
+===========================================
+
+### What to Download ###
+- [arduino IDE](https://www.arduino.cc/en/Main/Software)
+- [Eclipse IDE for C/C++ Developers](http://www.eclipse.org/downloads/packages/eclipse-ide-cc-developers/marsr)
+- [Java](http://www.java.com/)
+
+### Setup Arduino ###
+ see the [Readme](https://github.com/esp8266/Arduino#installing-with-boards-manager)
+ 
+### Setup Eclipse ###
+- [step 1](http://www.baeyens.it/eclipse/how_to.shtml#/c)
+- [step 2](http://www.baeyens.it/eclipse/how_to.shtml#/e)
+- go to Window --> preferences --> Arduino
+- add as private hardware path the Part to the ESP8266 (example: C:\Users\username\AppData\Roaming\Arduino15\packages\esp8266\hardware\esp8266)
+
+### Eclipse wont build ###
+if eclipse dont find the path to the Compiler add to the platform.txt 
+after:
+```
+version=1.6.4
+```
+this:
+```
+runtime.tools.xtensa-lx106-elf-gcc.path={runtime.platform.path}/../../../tools/xtensa-lx106-elf-gcc/1.20.0-26-gb404fb9
+runtime.tools.esptool.path={runtime.platform.path}/../../../tools/esptool/0.4.4
+```
+Note: 
+ - the path may changed, check the current version.
+ - each update over the Arduino IDE will remove the fix
+ - may not needed in future if Eclipse Plugin get an Update
+
+