Twitter: Change api version to 1.1.
Conflicts:
	plugins/Twitter/class.twitter.plugin.php
Don't allow user id override on post.
Added TrustedDomains() and SafeRedirect().
Conflicts:
	library/core/functions.general.php
Use SafeRedirect() instead of Redirect() in the discussion controller.
Merge branch '2.1' of github.com:vanillaforums/Garden into 2.1