Allow comments in /etc/mounts; ignore data under initrd/{ext2,fat}
Major ls changes! Support -R and print in columns

Lots of work. The column-printing isn't ideal (it's ugly if some files have
long names while most are shorter), but in many cases it's rather nice, and
in the others, it's okay.
In ALL cases, it's FAR better than the horribly ugly mess that it replaces!
ls: split do_dir into do_dir and print_entries
ls: print file arguments first; add -d, clean up; print stat errors
ls: update options; add TODO in shell; update .gitignore