1.15.1 protocol support (575) (#252)
* Add v1_15_1 for protocol 575
* Update for shifted packet IDs
https://wiki.vg/index.php?title=Pre-release_protocol&oldid=15213#Packets
https://wiki.vg/Pre-release_protocol
* Add SpawnMob packet variant, no metadata
* Add SpawnPlayer packet variant, no metadata
* Add block update actions comments, including beehive
* Add particle packet variant with 64-bit floats
* Add and handle join game and respawn packet variants, with hashed seeds
* Add chunk data packet variant with 3D biomes
https://wiki.vg/index.php?title=Pre-release_protocol&oldid=15213#Chunk_Data
"1024 biome IDs, ordered by x then z then d, in 4×4×4 blocks. Not
present if full chunk is false."
This is a fixed-size array of integers, but Rust doesn't yet support
generics over integers, so the 1024-element array doesn't support
fmt::Debug, hence we wrap it and implement fmt::Debug ourselves.
* Add load_chunk115 to not read chunk data structure biomes
https://wiki.vg/index.php?title=Pre-release_protocol&oldid=15213#Data_structure
dd2fb32df1