Refactor struct keyevent_t.

Fix mods with tap key but some problems still exists.

- 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)]

Add support partly for modifier with tap key.

Fix waiting_keys and periodical update for delaying layer.

Fix tap key using delaying_layer and waiting_key.

Add new layer actions.

Fix action of system and consumer usage.

Add initial fix for new keymap.

Fix image link 3 :(

Fix image link 2

Fix image link in README.md

Improve documentation

Fix usage of debug flag

Merge branch 'print'

Add print_dec() and debug_dec().

Add print utility

Merge branch 'sun'

Add extra commands Bell/Click to Sun converter

Add LED feature to Sun converter

Fix mousekey parameter bug