Many files:

Many files:
  ext2fs.h: Added function declarations and constants for bmap.c and
  	fileio.c.
  ext2_err.et.in: Added new error messages EXT2_FILE_RO and
  	EXT2_ET_MAGIC_EXT2_FILE
  Makefile.in: Added files bmap.c and fileio.c, and temporarily
  	commented out brel_ma.c and irel_ma.c
  bmap.c: New file which maps a file's logical block number to its
  	physical block number.
  fileio.c: New file which implements simple file reading and writing
  	primitives.
  alloc.c (ext2fs_alloc_block): New function which allocates a block,
  	zeros it, and updates the filesystem accounting records appropriately.