* Fractal: layout macro cleanup
Removed KEYMAP alias for LAYOUT_preonic_mit. Alias was unused, and the terminology usage is deprecated.
* Fractal: readme cleanup
Updated the line containing the documentation links in the readme.
* Fractal: disable preonic_mit community layout
QMK doesn't have a preonic_mit community layout at this time.
Disables preonic_mit as an option for community layout. Can be re-enabled when the layout is added.
* 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.
