boot system and buildkernel - Additional work

boot system and buildkernel - Additional work

* Make boot <directory> work.  Note however that dloader does not preload
  the kernel+modules so basically all you get here is the kernel and acpi
  with the current menu system setup.

  The dloader way (for the moment) is:

	cd kernel
	loadall
	boot

* Fix console=<blah>.  dloader was not mirroring the variable to the
  environment.  Also do the same for currdev, loaddev, and bootfile.
  (kernelname and module_path were already mirrored).

* Fix non-numeric menus.  'a' (kernel.alt), 'b' (kernel.bak),
  and 'R' (reboot).

* Space now halts the countdown.

* Add the boot-without ACPI option back into dloader.menu.

* Move the handling of the kernelname kenv variable out of machine
  specific code and into kern/init_main.c