Even with MY_DISABLED_SERIAL defined, the linker is still adding the
Serial object to the binary.
That's because a) the MySensors *.cpp files are actually included
into the sketch and compiled as part of it (and not compiled
separately and then linked) and b) due the the default(?) behavior of
the linker (https://github.com/arduino/Arduino/issues/4579).
Marcelo Aquino
Rainer Clasen
d00616
Olivier