Xmp-tool

* Fixed issue 4, 5 and related to XMPIterator, file_to_dict and
object_to_dict.
* Fixed issue in file_to_dict which didn't pass parameters to
XMPFiles.open_file() properly.
* Fixed issue 9 file_to_dict now raises IOError instead of returning
an empty dictionary for non-existing files. (*backward incompatible*)
* Fixed issue 8 - spelling mistake in function call in
XMPMeta.append_array_items
* Based on Exempi 2.1.1 and Adobe XMP Toolkit 4.4.2
* Thanks to olsenpk, pitymushroom, rmarianski, cfarrell1980 for bug reports
and patches

* Backwards incompatible with previous releases.
* Based on Exempi 2.1.0 and Adobe XMP Toolkit 4.4.2
* Initialise and Terminate should no longer be called before usage.

* First public release.


Change Log

Changes
- Actual release of the fixes to work with Python 3 that had been
previously committed. Trying to use the utility on Python 3 didn't
work because of missing parens after `print`.

Initial release