Priority of recognition of letter 'Щ' in GOST 1971 for Russian 

I have tried to make bidirectional transliteration using different systems and found out that GOST 1971 should do it correct. But in project's tests there is no correct checking of bidirectional transliteration for this system.

And my own tests shown that there was problem with priority of recognition of letter 'Щ'. 

$transliterator->cyr2lat('Щ'); // shh
$transliterator->lat2cyr('shh'); // Шh