Add helix keyboard (#2308)

* Fork from Let's Split

* Organizing files

* Delete some keymaps

* I2C and serial enabled at the same time

* Change readme

* add #define HELIX_ROWS for multiple rows

* Delete avrdude flashing script

* Delete makefiles

* Subproject elimination

* Fix lufa path

* Remove PLAY_NOTE_ARRAY usages to get rid of warning.

Fix conflicting function name

* Mousekey change default to off

* Fix to oled display adjust

* make rev2

change pin assign
change keymap

* use master_buffer

* Timing adjustment

* Organizing files

* Change Keymap

* Change Keymap

Add EISU and KANA
Correct 4rows

* NKRO default to disable

* EXTRAKEY_ENABLE default to disable

* add rgb reset key

* rgb custom function enable

*  Extend font

* add RGBLED_POWER

default folder to helix/rev2
RGB_ENABLE to no

* renamed directory

* Disable RGBLIGHT_CUSTOM_DRIVER

* Disable LOCKING_SUPPORT_ENABLE

* Update bootloader setting

* Change readme

* Fixed argument error

keyboards/helix/rev1/split_util.h

@@ -0,0 +1,24 @@
+#ifndef SPLIT_KEYBOARD_UTIL_H
+#define SPLIT_KEYBOARD_UTIL_H
+
+#include <stdbool.h>
+
+#ifdef EE_HANDS
+	#define EECONFIG_BOOTMAGIC_END      (uint8_t *)10
+	#define EECONFIG_HANDEDNESS         EECONFIG_BOOTMAGIC_END
+#endif
+
+#define SLAVE_I2C_ADDRESS           0x32
+
+extern volatile bool isLeftHand;
+
+// slave version of matix scan, defined in matrix.c
+void matrix_slave_scan(void);
+
+void split_keyboard_setup(void);
+bool has_usb(void);
+void keyboard_slave_loop(void);
+
+void matrix_master_OLED_init (void);
+
+#endif