Copying Things Files, using new yaml format, be future ready

See OH 3 Tips and Tricks, particularly the “Buying in Bulk” sections.

OH 4 is probably at least a couple of years away and there is no reason to think that .things files will be dropped even when we go to OH 4. For certain bindings, KNX being one of them, text based .things files make a lot of sense. So the most elegant solution is to leave them as they are.