HAL ported to FreeBSD

[Artem Kachitchkine]

I think some things can be done cleaner when put in an OS directory. 
Specifically, some method scripts are just easier to rewrite for the OS 
than add multiple if-then's (e.g. your patch to 
hal-system-lcd-set-brightness is almost as long as the script itself :)).

Same applies to method .fdi's: I'm not sure 
"computer:system.kernel.name" stuff is worth the trouble when it could 
just solve it at Makefile level by having different files for different 
OSes.

-Artem.