Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Shift+Ins - paste buffer
Shift+PrintScr - prev. screen

Add a keymap that is the standard ISO PC-101/3 layout, but with the
key marked "Caps Lock" acting as a left control key. Many want a control
key in the Real place, but still want the keymap to match the printed keys
as much as possible.