MAJOR: fundamental functions of the parser are ready and tested!

TO-DO:
1. follow the "TO-DO" comments to clean the code
2. filename should be NFFA-DI compliant like:
	nffa-di_NA01_Napoli_Na-26-015.h5
3. rheed data analysis should take two distinct functions
   one for the raw stream and one for the image
4. if time allows: consider moving most of main.py in separate modules

src/APIHandler.py

@@ -85,6 +85,7 @@ class APIHandler:
         """
         Downloads a specific attachment of a certain eLabFTW experiment (default) or item.
         Only returns its binary data. Use method download_attachment_to_disk to save to file.
+
         NOTE: Output is a dictionary where:
             * The key is the attachment's filename;
             * The value is the attachment's binary data.
@@ -100,7 +101,7 @@ class APIHandler:
             )
 
         config = elabapi.Configuration()
-        config.api_key["api_key"] = api_key
+        config.api_key["api_key"] = self.api_key
         config.api_key_prefix["api_key"] = "Authorization"
         config.host = self.elaburl
         config.debug = False
@@ -132,7 +133,7 @@ class APIHandler:
         """
         Downloads a specific attachment of a certain eLabFTW experiment (default) or item.
         Downloads their binary data through method download_attachments_data and dumps it to dump_dir.
-        Returns nothing on success.
+        Returns full path of the output file.
 
         Args:
             elabid:     eLabFTW internal ID of the selected resource.
@@ -151,9 +152,10 @@ class APIHandler:
         uploads = self.download_attachment_data(elabid, upload_id, entryType=entryType)
         for file in uploads:
             raw_data = uploads[file]
-            with open(os.path.join(dump_dir, f"exp{elabid}-{file}"), "wb") as f:
+            full_path = os.path.join(dump_dir, f"exp{elabid}-{file}")
+            with open(full_path, "wb") as f:
                 f.write(raw_data)
-        return
+        return full_path
 
 
 # Testing methods