Keyboard shortcuts

The keyboard system have 3 statuses:

1. Normal - nothing happened yet.
2. Ninja - the user typed q to start using keyboard shortcuts.
3. Line selected - the user selected the line to work on.

Key	Mode	Meaning
!	Any	Mark solution as checked.
q	Normal	Enter Ninja mode.
digits	Ninja	Select line number.
-	Ninja	Select last line.
q	Line selected	Add text using the fast selection side menu.
`	Line selected	Add free text to this line.
ESC	Any	Go back to normal mode.