- See https://github.com/tmk/tmk_keyboard/issues/60
- **Except for modifiers** a key pressed before the tapping starts should be released immediately
- 'Mod-Tap key'(like shift-;) didn't work from this fix: 4d0b3aa Fix Tapping: release of a key pressed before tap
This key sequence should register ':', not ';'. With the fix Shift is
released before settlement of tapping, this registers ';'.
    Shift   ~~___~~~~~~~
    ;(Tap)  ~~~____~~~~

- stuck tap key after tapping. seq[mods(d), key(d), mods(u), key(u)]
- tap key doesn't work when fast type. [key(d), mods(d), key(u),
  mods(u)]