Added support to enter bootloader from software (bootloader version must be newer than "v2.18Jun 22 2018 17:28:08" until workaround for older is created).
Updated CTRL and ALT keymaps for entering bootloader with Fn+b held for >500ms.
Added basic MacOS keymap for ALT.
USB sleep LED indicator now turns off after 1 second.
Slowed down debug LED code printing.
* swap KC_LALT with KC_LGUI
* replace KC_RALT with KC_RGUI
This makes the keyboard more mac friendly out of the box (I'm aware this
that this could partially be done in software with the preferences but
hey, where's the fun in that).