Adding the preferred copyright and license clause.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35837 a95241bf-73f2-0310-859d-f6bbb57e9c96

Adding MessageStatus class, meant to replace booleans passed around.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35835 a95241bf-73f2-0310-859d-f6bbb57e9c96