Hidmap is a generic HID item value to evdev event conversion engine that makes possible to write HID drivers in mostly declarative way with defining of translation tables.

This change includes following drivers:

• hms - HID mouse driver.
• hcons - Consumer page AKA Multimedia keys driver.
• hsctrl - System Controls page (Power/Sleep keys) driver.
• ps4dshock - Sony DualShock 4 gamepad driver.

And some drivers submitted by Greg V:

• hpen - Generic / MS Windows compatible HID pen tablet driver.
• hgame - Generic game controller and joystick driver.
• xb360gp - driver for Xbox360-compatible game controllers.

This revision is subset of https://reviews.freebsd.org/D27777