N64: Find ROM settings in database by ID, region and revision (MiSTer…

…-devel#830)

ID, region and revision are grabbed from the games' header and are looked up in the database text file, the same file where MD5 hashes are now. Both MD5 and ID will be valid ways of determining ROM settings, so old database files will still work. The benefit of this is that the database can be shrunk quite considerably, as many, many duplicates can be removed. It will be (much) easier to maintain. I'm hoping to see fewer pull request made to the database repository as a consequence of this change.