it supports four keyboards and two cascaded hubs

- Logical Min/Max contains signed value and needs 16 bit to indicate 255
https://github.com/jackhumbert/qmk_firmware/issues/312

Add converter for XT keyboards, fixes #309

- Add mac os garbage to git ignore.

Update config.h

Please see the post at https://deskthority.net/keyboards-f2/tmk-firmware-for-xt-keyboards-t13847.html

8da1898 Merge remote-tracking branch 'flabbergast/chibios'
f0fdd8a ChibiOS: update instructions.md.
24dd0b5 ChibiOS: update mk to match chibios/master.
cdee266 Merge branch 'develop' into chibios
221663c Fix signatre of layer state change hooks
5a364cb Merge branch 'hotfix-chibios' into develop
af664cd Merge branch 'newapi' into develop
04feeaa Clean hook codes
0ca106d Fix code and table in hook.txt
714d418 Add hook document from njbair's work
b715129 Chibios: add default location for chibios-contrib.
fb3a323 Merge branch 'master' into newapi
8b7fbbd Merge branch 'master' into develop
e49851a Chibios: add default location for chibios-contrib.

git-subtree-dir: tmk_core
git-subtree-split: 8da189851b

Match the changes in mainline chibios:
 - update chconf.h
 - update supplied ld scripts structure
 - update Teensy instructions (switch to official
    chibios and introduce contrib)

Add hardware serial support for sun_usb converter

It seems that the Sun Type 5c keyboard will not send the arrow key
codes if both shift keys are pressed.  To get bell and keyclick
working, I used Home/End as toggle keys instead.

Tested with a Sun Type 5c keyboard and a 7404 inverter.

Update macro names in bluefruit protocol

update macro names in bluefruit