Modernized lluictrl. Added LLViewModel. Fixed focus callbacks being called excessively. Updated LLButton, and implemented boost::signals2 to replace old callback handling.

indra/llui/llview.cpp

@@ -504,16 +504,6 @@ LLRect LLView::getRequiredRect()
 	return mRect;
 }
 
-//virtual
-void LLView::onFocusLost()
-{
-}
-
-//virtual
-void LLView::onFocusReceived()
-{
-}
-
 BOOL LLView::focusNextRoot()
 {
 	LLView::child_list_t result = LLView::getFocusRootsQuery().run(this);