add support for the OLPC mechanical non-membrane keyboard

add support for the OLPC mechanical non-membrane keyboard

Patch updated against current tree.

> From: Paul Fox <pgf@laptop.org>
> Date: Tue, 20 Jul 2010 16:22:40 -0400
> Subject: [PATCH] add support for the OLPC "mechanical" (non-membrane) keyboard
>  model(s). to aid in this, add keycodes/olpc with aliases to avoid needing to
>  use BKSL and TLDE, which don't appear anywhere near their "traditional"
>  position on the olpcm mechanical keyboards.