Update documents

git-svn-id: https://svn.code.sf.net/p/rubycocoa/svn/trunk/src@2614 f4f36d40-9719-0410-9868-dde021a23eda
Remove Thread additions never used

Thread additions works only on OS X 10.5 Leopard.

git-svn-id: https://svn.code.sf.net/p/rubycocoa/svn/trunk/src@2615 f4f36d40-9719-0410-9868-dde021a23eda