MQTT Client and longer messages

Argh, that's a pain. On the Espruino Wifi we enabled flow control (https://github.com/espruino/EspruinoDocs/blob/master/devices/EspruinoWiFi.js#L252-L288)... You could set up CTS:

Serial1.setup(115200, { rx: ..., tx : ..., cts : WIFI_CTS_PIN });
/// and enable (after WiFi inited) with
at.cmd('AT+UART_CUR=115200,8,1,0,2\r\n',500,function(d) { // enable flow control
                  if (d!="OK") throw new Error("UART_CUR failed: "+(d?d:"Timeout"));
                  // do the next thing now
                });

Trying with espruinio on an ESP32 seems to work much better although I'm now into issues with the waveform class

Hmm, yes, I'm not sure how well that works on ESP32...