<font face="Arial, Verdana">OK. With the new version I was able to compile it using Arduino 1.6.12. Didn't try on v1.8.1.</font>
NOTE: the new version would not compile unless the HAVE_HEATED_BED parameter was true ('1'). When it was false ('0'), the compiler threw the following error:
sketch/Commands.cpp: In static member function 'static void Commands::processMCode(GCode*)':
Commands.cpp:1648: error: 'heatedBedController' was not declared in this scope
else if(com->hasH()) Extruder::setHeatedBedTemperature(heatedBedController.preheatTemperature + (com->hasO() ? com->O : 0),com->hasF() && com->F > 0);
^
exit status 1
'heatedBedController' was not declared in this scope