+Support for Photographer/Editor Copyright as associative array as this is a new...

+Support for Photographer/Editor Copyright as associative array as this is a new feature the change (optionally being an array) has to be mentioned in documentation.
+New function exif_headername can be used to read the internal Tag namelist (was mainly created for debugging purpose but maybe somone writes code to create/update exif headers here).
+An internal version number is present.
+A testpage is supplied test.txt describes how the test works.
+The oldfunction read_exif_data has got an alias exif_read_data

As the old version of this module is very buggy i decided to implement the testpage (test.txt) and to create the alias. The test script only works with the alias as the old version does not pass tests. By the way it seems a good way to prepend 'exif_' to all functions in the module.