Writes the ``.sln`` file to disk.

def write(self):
        """
        Writes the ``.sln`` file to disk.
        """
        filters = {
            'MSGUID': lambda x: ('{%s}' % x).upper(),
            'relslnfile': lambda x: os.path.relpath(x, os.path.dirname(self.FileName))
        }
        context = {
            'sln': self
        }
        return self.render(self.__jinja_template__, self.FileName, context, filters)