Insideout design change
With this design change exiv2 clients will obtain ExifData and IptcData instances through an instance of Image (currently Image is use internally). This change will make Image the top level client interface to Exiv2.
The need for this change was driven by the addition of Iptc metadata support (and possibly others in the future). This change should make exiv2 easier to use with multiple metadata types and should also improve performance.