Keyboard driver implemented.

Most keys of the PS/2 keyboard are supported.  Numeric keypad is not, because the scancodes it produces matches the cursor keys, and I don't have software to change that.  The home/end/ins/del/pgup/pgdn keys are unsupported as well, since I don't have any logic to interpret the $E0 prefix byte.  Additionally, the ALT key is not yet supported either, although that's a very easy thing to add.  I just didn't do it because I feel I can use the remainder of the day for making something fun for MakerFaire instead.

However, function keys are supported, as are the SHIFT and CTRL keys.