Add all constants for the cURL module

This list of constants comes from the

    http://us2.php.net/manual/en/curl.constants.php

manual page.

Github-issue: 36
Run whitespace-cleanup on the source code

This patch contains no logic changes.  It only cleans up some
whitespace using a function of Emacs.
Highlight method calls using php-function-call-face

There is already a regular expression to highlight method calls in
php-font-lock-keywords-3 but the expression for highlighting member
variables comes first in the list.  Because of their similarity the
expression for member variables always matches method calls first.  We
can fix this by simply changing the order of the expressions in the
php-font-lock-keywords-3 list so that the more specific regular
expression, the one for method calls, comes first.

Github-issue: 46
Clarify that constants from all PHP extensions are not highlighted
Link to the GitHub page in the README for reporting issues

The document says ‘here on the Github page’ but not everyone will look
at the README from the online page.  So we should link to it so the
people looking at the plain-text version know where to go to report
issues and bugs.