This has the triple bonus effect of a) making a lot of code easier to read, b) reducing Server::getInstance() usages, and c) removing a whole bunch of Server dependencies.
The network and block namespaces are untouched by this commit due to potential for merge conflicts. These should be dealt with separately on master.
it's no longer necessary to force-write these, since the NBT is now ephemeral. Any tag type mismatches should be dealt with on read, after which the original tag will be discarded anyway.
