Add USB HID keyboard press and release variants that work with USB HID
Keyboard Keycodes. This makes it possible to send HID key events for
keys that don't appear on a traditional US 104 key keyboard.

This patch is a somewhat rototilled version of the patch linked below.
In particular, i dropped whitespacechanges from the original patch and
changed 0x01 and 0x00 in the code to 1 and 0 to better match the style
of the surrounding code.

Based on patch
https://github.com/weizenspreu/Arduino/commit/1ede2b8abd7c3b74ffc75f28da38b4acdc4817f2.patch
from Pull request 1391.