Titelwarnung 2.3.1

Fix URL detection in title warning by using regex pattern matching

Replace word-splitting approach with regex-based matching:
Phrases with special chars (URLs, etc.) match as substrings
Regular words match with word boundaries (\b)

Support XF2.3
Min require XF2.3
Fixed extension
Now if a word contains a forbidden word, it is checked because it can only be a part, perhaps in the future there will be support for lemmas
Using string helpers from XF