Proper block hitboxes when using block_in_hitbox config option

[Skurvandrer]

The server allows a player to place a block so that it intersects with the player, which causes the player to be moved up or along to clear the block, or, if the block is placed at head height, causes them to crawl.

The notchian server will not allow blocks to be placed in these circumstances.

[StackDoubleFlow]

It would be great to have this as a config option. It's sometimes nice to be able to place blocks in your hitbox when building.

[EwanFox]

Added in #70

[StackDoubleFlow]

#70 is a step in the right direction for this issue, but different blocks have a different collision box and we don't quite handle them all yet. For example, in vanilla, you can place a redstone wire on the block you're standing on.

It would be nice to have a more robust collision system in the future, so this issue will remain open.