[ticket/12753] Add invalid chars string for ALPHA_DOTS and ALPHA_PUNCTUATION

PHPBB3-12753
Merge pull request #2632 from Dragooon/ticket/12753

[ticket/12753] Add invalid chars string for ALPHA_DOTS and ALPHA_PUNCTUAION

* Dragooon/ticket/12753:
  [ticket/12753] Add invalid chars string for ALPHA_DOTS and ALPHA_PUNCTUATION