Using esp32-arduino-lib-builder to compile custom libraries

Espressif has provided a tool to simplify building your own compiled libraries for use in Arduino IDE (or your favorite IDE). To use it to generate custom libraries, follow these steps:

1. git clone https://github.com/espressif/esp32-arduino-lib-builder
2. cd esp32-arduino-lib-builder
3. ./tools/update-components.sh
4. ./tools/install-esp-idf.sh (if you already have an $IDF_PATH defined, it will use your local copy of the repository)
5. make menuconfig or directly edit sdkconfig.
6. ./build.sh

The script automates the process of building arduino as an ESP-IDF component. Once it is complete, you can cherry pick the needed libraries from out/tools/sdk/lib, or run tools/copy-to-arduino.sh to copy the entire built system. tools/config.sh contains a number of variables that control the process, particularly the $IDF_BRANCH variable. You can adjust this to try building against newer versions, but there are absolutely no guarantees that any components will work or even successfully compile against a newer IDF.