[added] Ability to send up to 3 buttons on MessageBox SUI. 
(Temporary until SUI restructuring is finished.)
[added] Structured LUA SUI sending of messagebox-type similar to
listbox-type, to allow for up to 3 button messageboxes.

Change-Id: I885349d7e7248f9c5a81d0646ecae4416d822a63
Merge "[added] Ability to send up to 3 buttons on MessageBox SUI.  (Temporary until SUI restructuring is finished.) [added] Structured LUA SUI sending of messagebox-type similar to listbox-type, to allow for up to 3 button messageboxes." into unstable