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/sixkeyboard/sixkeyboard.h

@@ -15,8 +15,4 @@
 // instead of the obtuse 11x8 matrix.
 
 
-void matrix_init_user(void);
-void matrix_scan_user(void);
-void led_set_user(uint8_t usb_led);
-
 #endif