* Impl Seek for reader in Decode Trait
* Add support for Slot data type
* Update tests and rust fmt
* Add tests for Slot
Also fixed bugs I found while testing
* Update slot signature
* Resolved requested changes
Updated decode trait signature and removed unnecessary getters/setters in `Slot`
This change was made to make it easier for invariants to be upheld. When
the spatial partition is added, we can ensure that changes to entities
are immediately reflected in the partition. Additionally, chunks being
shared between worlds was a leaky abstraction to begin with and is now
removed. A method in `Config` is now necessary to determine what world a
client should join.
Along with this, most mutable references have been wrapped in a newtype
to ensure that `mem::swap` cannot be used on them, which would break
invariants. This is analogous to `Pin<&mut T>`. The reason we can't use
Pin directly is because it would require unnecessary unsafe code
within the library.