Enrich twitter username validation documentation
Don't nest what doesn't need nesting
Relates #972 - Individual users can be excluded from sitemaps
Simplify admin menu access determination
Merge branch 'master' of git://github.com/Yoast/wordpress-seo into Mini-tweaks

Conflicts:
	inc/wpseo-non-ajax-functions.php
User-roles also can be excluded from sitemap
Cleaned up too much, fixed it.
We're in a time of infinite space!
Which means that we're no longer removing newlines and returns from the `post_content`, which in turn means we should make sure that we use the `s` modifier for regexes that need to cross multiple lines as otherwise the `.` doesn't match newlines. Fixes #1416
Also stopped stripping tags in the `get_first_paragraph()` method, as that would basically break the whole concept.
Updated Polish. Once moar.
Updated Croatian translation
Several code improvements
Code style
Add validation for OpenGraph title, related to #1424
Fix image upload input name, related to #1424
Properly outputting value of option, fixes #1424
Image URLs can't be FTP, so changing sanitization method
"Ugh" code standards.
Replace `%%parent_title%%` variable client side through JS.
code style fix + update of change log.
Bluntly override `woo_title`'s output. Fixes #1423
Partially fix issue #1428