First version of save function + unit tests

Finished first version of qim3d.io.save() + unit tests. I am not sure what self.verbose is intended to do, so for the moment, I have just left it unused in init()

qim3d/io/save.py

@@ -31,7 +31,6 @@ class DataSaver:
             compression (bool, optional): Specifies if the file should be saved with Deflate compression.
                 Default is False.
         """
-        self.verbose = kwargs.get("verbose",False)
         self.replace = kwargs.get("replace",False)
         self.compression = kwargs.get("compression",False)