Backlight abstraction and other changes (#439)

* redoes matrix pins, abstracts backlight code for B5,6,7

* slimming down keyboard stuff, backlight breathing implemented

* don't call backlight init when no pin

* cleans up user/kb/quantum calls, keyboard files

* fix pvc atomic

* replaces CHANNEL with correct var in breathing

* removes .hexs, updates readmes, updates template

* cleans-up clueboards, readmes to lowercase

* updates readme

keyboards/kc60/keymaps/stanleylai/readme.md

@@ -4,7 +4,7 @@ Stanley Lai's Split Right Shift with Dedicated Arrow Keys
 ![Image of KC60 with RGB Underglow](../ws2812/ws2812_example.jpg)
 
 ## Quantum MK Firmware
-For the full Quantum feature list, see [the parent README.md](/README.md).
+For the full Quantum feature list, see [the parent readme.md](/readme.md).
 
 ## Keymap Notes
 - Keymap setup with split Right Shift in mind.