Add a new category resp. icon for "Car" / "Automobile"

[andrewfg]

There increasingly more and more addons for monitoring the state and functionality of cars. The current range of categories is completely related to buildings and their contents. => So I think we need to add a category for "Car" / "Automobile".

[florian-h05]

See openhab/openhab-distro#1688 for some related discussion.