Copy over the block ids using memcpy instead of a for loop

Sadly this changes the chunk structure, essentially breaking everything.
It theory it'll speed stuff up though. And yes that for loop is there as
we still have to split stuff up to get the correct data values.

Signed-off-by: Toon Schoenmakers <nighteyes1993@gmail.com>
Applied memcpy to the biomes array as well

Signed-off-by: Toon Schoenmakers <nighteyes1993@gmail.com>