lots of cleanup

don't increase length of directory

no more cons_put system calls
usertests tests two processes writing files

so fast interrupts overflow the kernel stack
fix: cli() before lapic_eoi()

ioapic

iget
mkfs makes a file system image
put this in your .bochsrc:
ata0-slave: type=disk, mode=flat, path="fs.img", cylinders=1024, heads=1, spt=1