revision of nlines method

src/icartt/dataset.py

@@ -189,13 +189,13 @@ class StandardNormalComments(collections.UserList):
     @property
     def nlines(self):
         """calculates the number of lines in the normal comments section"""
-        n = 1  # shortnames line
-        n += len(self.freeform)  # freeform comment
+        # shortnames line is always there:
+        n = 1
+        # freeform comment might or might not be there:
+        n += sum(len(s.split('\n')) for s in self.freeform)
+        # tagged comments have at least one line:
         for k in self.keywords.values():
-            try:
-                n += len(k.data[0].split("\n"))  # and keywords might be multiline...
-            except IndexError:  # ok we have no list,
-                n += 1  # just add 1
+            n += sum(len(s.split('\n')) for s in k.data) or 1
         return n
 
     @property