show/showAll methods now use Canvas instead of SDL_Surface

- added compatibility method to Canvas to allow SDL_Surface access
- added drawBorder method to Canvas to replace CSDL_Ext method
- added drawColor method to Canvas to replace CSDL_Ext method
- minor changes to Tavern and Trade windows to adapt to new API

mapeditor/BitmapHandler.cpp

@@ -42,8 +42,6 @@ namespace BitmapHandler
 
 	QImage loadH3PCX(ui8 * pcx, size_t size)
 	{
-		//SDL_Surface * ret;
-		
 		Epcxformat format;
 		int it = 0;