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
* Use extra comptible = "zmk,behavior-global" to add
behaviors to global bindings for event notification.
* Implement mod-tap, as a keymap binding and global one
to skip tap if other keycode pressed while held.
