The key enable caps lock immediately. It does nothing if caps lock is
already enabled.
It is not present on the keyboard by default but a place is defined on
every layout, top-right of the shift key. It can be enabled in the
settings.
The icon is from materialdesignicons.com.
The '0' has been moved because it was hard to type due to being close to
the edge of the screen.
This is fixed in a more elegant way in a27c644, there's no reason to
keep the '0' in an inconsistent place anymore.
