Bring in udev & libdevattr

* Bring in kern_udev, libdevattr and udevd from my personal repo. This
is still WIP, but basic functionality is available and the API is
stabilizing.

* kern_udev allo

Bring in udev & libdevattr

* Bring in kern_udev, libdevattr and udevd from my personal repo. This
is still WIP, but basic functionality is available and the API is
stabilizing.

* kern_udev allows the association of certain parameters in form of a
dictionary to each device in the system and provides notification of
attach and detach events.

* udevd is a userland daemon which keeps an up to date list of all
devices and their dictionaries and provides an interface for
libdevattr to acccess and manipulate these devices and related events.

* libdevattr provides a mostly Linux' libudev compatible API to access
device dictionaries and events. Beware that it is NOT a full drop-in
replacement!

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