The MQTT library seems to only work for building with firmware level 0.4.5. Anything after that, you get a bunch of errors like this.
../hal/src/stm32f2xx/deepsleep_hal_impl.h:23:60: error: section attribute not allowed for '<anonymous>' #define retained __attribute__((section(".retained_user")))
I’d like to use MQTT for both the Photon and the Electron. Is there another MQTT implementation people are using?