Remove textboxwrap() and wrap() return value

This removes Graphics::textboxwrap(), as it is now an unused function.
Additionally, this removes the return value of textboxclass::wrap(), as
it is also now unused.

desktop_version/src/Graphics.h

@@ -102,8 +102,6 @@ public:
 
     void textboxcentery(void);
 
-    int textboxwrap(int pad);
-
     void textboxpad(size_t left_pad, size_t right_pad);
 
     void textboxpadtowidth(size_t new_w);