Minor code clean up PHP and HTML files in w/

* Consistently use 'require_once' and 'require' fo the inclusion
  of MWVersion and WebStart (extra2.php used 'include' still).

* {favicon,touch}.php
  - Add doctype to avoid quirks mode.
  - Remove redundant html/body tag.
  - Do escaping closer to output.

* Whitespace, single quotes.

* 'require' and 'require_once' are not functions.

Change-Id: Ifbfb7dfd8fc0cd822b084d955f8afdbc51f26522