prefixed  global in title override method
add title separator option and use that instead of the  global
simplify logic to strip all title tags
fix og_title test
cleanup unused code
Merge branch 'master' into title-separator

Conflicts:
	css/yst_plugin_tools.min.css
	inc/wpseo-functions.php
	tests/test-class-opengraph.php
Merge branch 'master' into title-separator
Put the separator options in a class variable, created a getter and made the array filterable.
Use the WPSEO_Option_Title class variable instead of a static array.
Added separator validation.
Made the preg_replace used on force_rewrite titles non-greedy
Use the correct separator in retrieve_sep()
Stop supporting the GLOBAL 'sep'
Prevent user filter of separator options breaking option validation
Fix typo
Fix validation of separator

- original $clean value is already the default, so does not need to be set
- validation only needs to be performed if field has been received
Use the separator default as defined in the options class
Simplified the regex even more
Re-use logic in replace class for retrieving the separator

Stabilizes the functionality
Merge branch 'master' of git://github.com/Yoast/wordpress-seo into title-separator

Conflicts:
	frontend/class-frontend.php