Removal of inter-server SP transfers

[Balrog]

Because we want the new shard or server to be a fresh start when it's been made, I'm going to remove the ability to transfer shop points between servers. I could've made it so you can transfer to certain servers or shards and not others but it will just confuse people and cause complaints from people that bought SP with the intention of transferring them, so it's easier to just disable transfers altoghether.

I'm trying to get as many small changes as I possible done before I start working on the sharding system, because that will take months and once I start, it will be hard or maybe impossible to make other changes to the code while it's still ongoing. So I will make this change soon but I wanted to give everyone a few days' notice, because there are probably a few people with SP on their WSBG account who intend to transfer them but haven't got round to it yet - please do that quickly if you are one of them.