Better match PHP's \s expression when parsing optional spaces.

The \s expression matches form feed.  Also changed a few space productions
to space_and_newline where I could tell by inspection of the PHP parser
source (and testing on a local mediawiki install) that \s was used and
newlines should be permitted.

Change-Id: Ifd06542356dfbda4d069c8f320bf1ac797688bbc
Merge "Better match PHP's \s expression when parsing optional spaces."