Implement SpawnMobPacket, Entity & Vehicle Movement Relevant Packets

[zacholade]

Hello again. :) Had a bit of time this week to implement some new packets.

• SpawnMobPacket I used PrismarineJS/minecraft-data and created a little script to generate the ids of each entity for every major protocol version. It appears the id's for the entities in SpawnObjectPacket.EntityType may need updating, however will make another PR if this is the case. This being said, I'm not sure of the accuracy of Prismarine's data because it seems to be missing the id for wither_skeleton in some protocol_versions. Other than this I didn't notice any issues here. I've attached the json my script produced; however note that there are some duplicates and some entities changed name in some protocol versions so takes some looking around if used. https://hastebin.com/icuragepin.json vs = protocol version id = id iid = internalId

• PositionLookAndDirection addition. I added a new utility type for handling the additional head_pitch attribute in the SpawnMobPacket. While this has benefits for the user I feel it may fairly obsolete and the user can simply access PositionAndLook as usual and the additional head_pitch attribute seperately.. It also overcomplicates this part of the packet to some extent. Feel free to suggest removing it from this PR.

• The rest of the packets are pretty straightforward... Hope there are no major concerns. Had a lot of fun doing this and learnt about the magic of descriptors (used in SpawnObject and SpawnMob) in doing so.

[coveralls]

Coverage increased (+0.08%) to 97.342% when pulling 6a7c6653849a7ebbc6717621638e49b8a325b79c on SirGhostal:new-packets into 6f2f25656c5c06fb4e5bd2be6fb1b0b2c2966ee5 on ammaraskar:master.