Keyboard: Add Nyquist Rev 3 (#4287)

* Add Nyquist Rev 3

* Switch to split_common

keyboards/nyquist/nyquist.h

@@ -1,5 +1,4 @@
-#ifndef NYQUIST_H
-#define NYQUIST_H
+#pragma once
 
 #ifdef KEYBOARD_nyquist_rev1
     #include "rev1.h"
@@ -7,6 +6,9 @@
 #ifdef KEYBOARD_nyquist_rev2
     #include "rev2.h"
 #endif
+#ifdef KEYBOARD_nyquist_rev3
+    #include "rev3.h"
+#endif
 
 #include "quantum.h"
 
@@ -26,4 +28,4 @@
         KC_##L40, KC_##L41, KC_##L42, KC_##L43, KC_##L44, KC_##L45, KC_##R40, KC_##R41, KC_##R42, KC_##R43, KC_##R44, KC_##R45 \
     )
 
-#endif
+#define LAYOUT_kc_ortho_5x12 LAYOUT_kc