Chunk property naming (.dims abbreviation)

[timoxley]

.dims is abbreviated, yet .position and .voxels is not. Should probably abbreviate them all or spell them all out.

dims: Array[3]
position: Array[3]
voxels: Int8Array[64]

[max-mapper]

+1

[deathcap]

If the chunk format is changed to use ndarray max-mapper/voxel#18 then dims will become shape