Database corrections

[Wake]

I've just made the following changes to the database:

551: Cover artist John Higgins, not Brendan McCarthy.
623/624: Cover artist Will Simpson, not Steve White.

I know there have been other corrections mentioned in the cover votiong threads, but I can't find them at the moment. Also, I'm assuming any corrections are themselves correct. If there is any doubt, please let me know.

Cheers,

Wake