Remove pointless 'len' parameter from read_mbr and write_mbr.
Make read_mbr initialise mbr if it can't be read (delete MD code).
Make i386 always ask at least once about the bootcode.
Move LIB_MOVE and LIB_COUNT from md.h to aout2elf.c
Make same function return useful defaults if it can't find an answer.
Make all ports default to the useful defaults if bios geometry is unknown.
Move some messages to mbr set from mi set.
Fix i386 code that selects which bios disk, simplify interface to menus.
Remove now unnecessary global data from many ports.