git clone -b v3.3 --recursive https://github.com/espressif/esp-idf.git
set -x IDF_TOOLS_PATH /home/martin/code/swimtracker-firmware/idf-tools
cd esp-idf
./install.fish

# install arduino
mdir components
cd components
git clone https://github.com/espressif/arduino-esp32.git arduino

# to get into environment (works only bash?)
export IDF_TOOLS_PATH=/home/martin/code/swimtracker-firmware/idf-tools/
.  /home/martin/code/swimtracker-firmware/esp-idf/export.sh


+ use only arduino libraries that are really necessary => smaller firmware 

-> result: new esp-idf version doesn't work together with arduino-esp
-> use 3.3? 
-> not yet clear: how to use arduino component libraries