Exiv2

As discussed in http://dev.exiv2.org/boards/3/topics/1039 I suggest the schemas of Microsoft Photo 1.2 Region* and the Regions schema of the Metadata Working Group to be added to exiv2. These schemas become more and more used by Software like Picasa (built in since version 3.9, with extra tools before 3.9), Windows Live Photo Gallery aso. The tags can be used to tag people, pets, camera focus, etc. information with textual information and in-photo location. I add a diff for the current code revision to this issue and will provide a complete example later. First examples can be found in the quoted forum topic.