Here is how to reproduce the problem:

Use:

• Latest (as of this write-up; SD Built-In by Arduino, Sparkfun 1.08) standard SD Card library from Arduino.
• Latest MySensors libraries (2.0.0).

Try to compile the following sketch:
#include <SPI.h>
#include <SD.h>
#define MY_RADIO_NRF24
#define MY_SOFTSPI
#include <MySensors.h>

The following error is reported:
DigitalPin.h:41:8: error: redefinition of 'struct pin_map_t'

Maybe something should be conditionally included inside MySensors.h or thereafter within.
Otherwise, most likely it will clash with other libraries that include the same thing(s).

Cheers,
Jordan

I wrote my own MQTT Client Gateway which runs on ESP8266, trying to minimize the difference from the MQTTGateway in the MySensors Examples. It uses Nick O'Leary's MQTT Client. I put it up at https://github.com/jordan-public/MySensors-MQTTCGW along with instructions for setting it up. If anyone wants to use it, you are welcome to it.

Jordan