Improve detection of empty lines

Search with RegEx as empty lines could also contain spaces

Related Task: [FS#141](https://fs.golderweb.de/index.php?do=details&task_id=141)

bots/markpages.py

@@ -26,6 +26,7 @@ Bot to mark pages which were/are subjects of redundance discussions
 with templates
 """
 
+import re
 from datetime import datetime
 
 import pywikibot
@@ -226,8 +227,8 @@ class MarkPagesBot( CurrentPageBot ):  # sets 'current_page' on each treat()
                 # Filter one linebreak
                 if isinstance( self.current_wikicode.get(
                     insert_after_index + 1), mwparser.nodes.text.Text ) and \
-                    self.current_wikicode.get(
-                        insert_after_index + 1 ).value is "\n":
+                    re.search( r"^\n\s+$", self.current_wikicode.get(
+                        insert_after_index + 1 ).value ):
 
                     insert_after_index += 1