Switch STROKE_FONT::Draw() to take "const wxString&" rather than "wxString" by value.

common/gal/stroke_font.cpp

@@ -147,7 +147,7 @@ BOX2D STROKE_FONT::computeBoundingBox( const GLYPH& aGLYPH, const VECTOR2D& aGLY
 }
 
 
-void STROKE_FONT::Draw( wxString aText, const VECTOR2D& aPosition, double aRotationAngle )
+void STROKE_FONT::Draw( const wxString& aText, const VECTOR2D& aPosition, double aRotationAngle )
 {
     // Context needs to be saved before any transformations
     m_gal->Save();

include/gal/stroke_font.h

@@ -70,7 +70,7 @@ public:
      * @param aPosition is the text position in world coordinates.
      * @param aRotationAngle is the text rotation angle.
      */
-    void Draw( wxString aText, const VECTOR2D& aPosition, double aRotationAngle );
+    void Draw( const wxString& aText, const VECTOR2D& aPosition, double aRotationAngle );
 
     /**
      * @brief Set the glyph size.