BToolBar: Add a "text" parameter.

For defining the text that appears alongside the icon.

This function really has too many parameters; we probably should break
it out into a BAction class...

headers/private/shared/ToolBar.h

@@ -24,10 +24,12 @@ public:
 			void				AddAction(uint32 command, BHandler* target,
 									const BBitmap* icon,
 									const char* toolTipText = NULL,
+									const char* text = NULL,
 									bool lockable = false);
 			void				AddAction(BMessage* message, BHandler* target,
 									const BBitmap* icon,
 									const char* toolTipText = NULL,
+									const char* text = NULL,
 									bool lockable = false);
 			void				AddSeparator();
 			void				AddGlue();