Remove all `@inbounds` – this is not a hotspot, nor sufficiently safe

When you're doing this much I/O, bounds checking is a completely trivial overhead, so having `@inbounds` annotations everywhere is an unnecessary optimization. There are also lots of instances in this code using indexes that are by no means certain to be in bounds. I just encountered one that was causing very hard to debug problems as it was basically trashing the surrounding memory.