code refactor

related to #8 (closed):

• I kept changes per commit small, so the number of commits got kind of numerous...

src/icartt/dataset.py

@@ -926,6 +926,8 @@ class Dataset:
             else:
                 self.inputFhandle = f
 
+        # TODO should we add a filename characters check, as we have it for the variable names?
+
             self.readHeader(splitChar)
             if loadData:
                 self.endDefineMode()