Use multidimensional arrays instead of a continuous block of memory.

[Xaymar]

Since in the end all we do is store a pointer, using a continuous block of memory has near to no performance improvements on most of todays hardware.
It would probably be better to switch to a multidimensional array instead.

[Xaymar]

First attempt in 4.5, seems to randomly crash when accessing some of the arrays. Possibly garbage collection happening, if that even affects it.
Code works outside of Unreal Engine 4.5, so no idea why this isn't working right.