Use Page::HTTP_STATUS_XXX to refer to values
Use $this->setHttpStatus() for frontend 404 and 403 page types
Use the same default value as the SymphonyErrorPage constrctor
Use sprintf instead of vsprintf
Convert most of the errors to the new throwCustomError; Set nice http status for all of these
Switch $heading and $message param order to match more the SymphonyErrorPage constructor function; Since throwCustomError is a new method, it is ok!
Use lowercase nulls
Fix stupid mistakes (param names) and added some more http status output by default
Remove all throw new SymphonyErrorPage and replace them with a call to throwCustomError
Make the "type" checking a bit more safe; Made the heading translatable