Porting Espruino to a new device

To be honest it could be anything - it's not really an Espruino problem at all. It might help to figure out exactly how it's crashing. I'd step through _start instruction by instruction and figure out where it dies.

All I can think right now is that _start - which I guess is provided by Nordic - expects some variables to exist that might have been defined in linker.ld. Espruino's version of the linker file might not define the correct ones, or might use different names.