* Remove chording as it is not documented, not used, and needs work.
* Make Leader Key an optional feature.
* Switch from `PREVENT_STUCK_MODIFIERS` to `STRICT_LAYER_RELEASE`
* Remove `#define PREVENT_STUCK_MODIFIERS` from keymaps.
* add ortho_4x12 symbolic layout
* delete trash
* modify little bit
* fixed doesn't requires
replace `#ifndef ... #endif` to `#pragma ones` in config.h
delete `QMK_KEYBOARD_CONFIG_H` in config.h
delete `action_layer.h` and `eeconfig.h` in keymap.c
