Added VIC target
Make the VIC code more like Xinu's
Added Xinu interrupt routines
Added target for Xinu interrupt routines
Modified tests to use the Xinu interrupt routines. Enabling interrupts does not yet seem to work/
Marged in Xinu interrupt routine resources
Renamed the ARM IRQ enable and disable routines so they don't clash with the ones from Xinu.
Re-moulded to the way Xinu expects a VIC to operate