This adds an irqhelp library for simplified user irq registration. The second patch implements the use case for ddekit (netdde).
TESTED: Copied 170000 files totalling 11GB inbound. ... sent 10,932,485,258 bytes received 3,563,749 bytes 1,473,960.38 bytes/sec total size is 11,194,873,873 speedup is 1.02 Also tried ifdown and ifup a few times, works as before. Thanks, Damien
