(php-beginning-of-defun-regexp): Fix regular expression that is
failing to match identifiers in function definitions for Imenu and
add-change-log commands.
(php-keywords): Remove "private" since its handled like
"protected" and "public", not as a generic keyword.
(php-font-lock-keywords-1): The use of grouping in the regular
expression for php-constants and php-keywords added on 2008-04-12
requires referencing the group number to highlight, otherwrise the
entire match is highlighted.
