Ground work for larger file systems, and miscellaneous fixes:

Ground work for larger file systems, and miscellaneous fixes:
- MFS and mkfs(1) now perform extra sanity checks
- fsck(1) can now deal with inode tables extending beyond the file
  system's first 4GB
- badblocks(8) no longer writes out the superblock for no reason
- mkfs(1) no longer crashes when given no parameters
- more(1) no longer crashes when standard output is redirected