Functionality to copy existing signatures erroneously removed

When installing, Signatures for forums starts with empty signatures for all users. But often signatures are already in use. To prevent users creating new signatures, it would be nice to copy the current signatures over on install. That would also be symmetrical with de-installing Signatures for forums as that already neatly copies its table back over to the users table.

I've added this to signature_forum.install right after the table create:

db_query("INSERT INTO {users_signature} (uid, signature) SELECT uid, signature FROM {users} ");