Try to open a preview of the generated document.
        Currently only supported on Windows.

def open_preview(self):
        '''
        Try to open a preview of the generated document.
        Currently only supported on Windows.
        '''
        self.log.info('Opening preview...')
        if self.opt.pdf:
            ext = 'pdf'
        else:
            ext = 'dvi'
        filename = '%s.%s' % (self.project_name, ext)
        if sys.platform == 'win32':
            try:
                os.startfile(filename)
            except OSError:
                self.log.error(
                    'Preview-Error: Extension .%s is not linked to a '
                    'specific application!' % ext
                )
        elif sys.platform == 'darwin':
            call(['open', filename])
        else:
            self.log.error(
                'Preview-Error: Preview function is currently not '
                'supported on Linux.'
            )