My config is:
- In make menuconfig, the python command is simply 'python'
- In Eclipse, set the PATH to point to the Python3.5 environment.
- Make sure pyserial is installed for Python 3.5. This happens when you run setup.py in esptool. From the esptool readme:
esptool.py depends on [pySerial](https://github.com/pyserial/pyserial#readme) version 2.5 or newer for serial communication with the target device.
If you choose to install esptool.py system-wide by running `python setup.py install`, then this will be taken care of automatically.