Return character at *position* with the given offset.

def get_character(self, position, offset=0):
        """Return character at *position* with the given offset."""
        position = self.get_position(position) + offset
        cursor = self.textCursor()
        cursor.movePosition(QTextCursor.End)
        if position < cursor.position():
            cursor.setPosition(position)
            cursor.movePosition(QTextCursor.Right,
                                QTextCursor.KeepAnchor)
            return to_text_string(cursor.selectedText())
        else:
            return ''