Remove unnecessary copy ctors/copy assignment operators

C++11 deprecates having one without the other.
Eliminates many, many GCC -Wdeprecated-copy warnings.

include/wx/richtext/richtextbuffer.h

@@ -1312,11 +1312,6 @@ public:
     */
     wxTextBoxAttr() { Init(); }
 
-    /**
-        Copy constructor.
-    */
-    wxTextBoxAttr(const wxTextBoxAttr& attr) { Init(); (*this) = attr; }
-
     /**
         Initialises this object.
     */