Change the concatenation format to columns

[tokee]

Pyramid data are currently concatenated by appending data from a pyramid to the existing data: a1x1, a2x2, a4x4, ..., a128x128, b1x1, b2x2, b4x4, ..., b128x128 This means that accessing tile data for a given level from two pyramids next to each other, e.g. a2x2 and b2x2 means a lot of skipping through the concatenation file.

Storing the data column-wise a1x1, b1x1, a2x2, b2x2, a4x4, b4x4, ..., a128x128, b128x128 raises the chance of tiles on the same level being near to each other and therefore cached together.