Aligns *.h and *.c to underscore naming convention.
These were kept (with warnings) for backwards compatibility with external boards/shields:
- kscan-mock.h
- matrix-transform.h
They should be removed in the future.
PR: #523
* Fire an event w/ layer number, state, and timestamp
when a layer is activated/deactivated.
* Add `zmk_keymap_highest_layer_active()` query.
Co-authored-by: KemoNine <mcrosson@kemonine.info>