* 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.
* planck with a not-quite-neo layout for a de-DE OS/SW keymap
* ergodox infinity with a not-quite-neo layout for a de-DE OS/SW keymap
* add documentation