Annotate a few AppKit members with ThreadSafe
Annotate a few AppKit members with ThreadSafe

See comments on this commit:
https://github.com/mono/monomac/commit/2a986b2286adae0695cb26722483ca9b57e0172e

And bug 10604:
https://bugzilla.xamarin.com/show_bug.cgi?id=10604

PlayScriptRedux/monomac,dlech/monomac