Bug fix : Set the coordinates of the centre in px to int (consequence of the commit 71d8431d regarding the future division operator)

If the data passed in argument is a file-uri, then the file is loaded. The function accept now also the binary-dump as argument

Move the field formatting (string or partial hex representation) in a function (overloading possible for user-definded fields).

If the resolution is not stored in the image passed in parameter, try to load the resolution from the NIST object

If the compression algorithme is already stored in the GCA field, it will be retured. If the value can't be decoded, a KeyError is raised

Store the file name in the self.filename variable, and the complete path in the self.fileuri variable

Rename the functions set_name() and get_name() to set_identifier() and get_identifier(), and move in the 'traditional' module.