Change dev read/write functions
to take inode* instead of minor number.

Unlock console inode during console_read
and console_write.  Otherwise background
processes cannot write to console while the
shell is reading it waiting for input.

No one is going to find this inode.
There is only one ref to it -- the caller --
and no links to it.

Mainly delete unused constants and code.

Move mp_startthem to main.c as bootothers.