Auto-deactivate plugin if SPL extension not available (prevent white-screen).
Fix issue 1160 - php notice / score title in publish box unavailable if post = noindex

Was a minor regression caused by pull request #1035.
Merge branch 'master' of git://github.com/Yoast/wordpress-seo into Auto-deactivate-if-no-SPL

Conflicts:
	readme.txt
Merge branch 'master' of git://github.com/Yoast/wordpress-seo into Issue-1160-undefined-notice

Conflicts:
	readme.txt
Merge pull request #1162 from jrfnl/Auto-deactivate-if-no-SPL

Auto-deactivate plugin if SPL extension not available
Merge pull request #1164 from jrfnl/Issue-1160-undefined-notice

Fix issue 1160 - php notice / score dot title in publish box