Improve ordering of parsers in core

[duesee]

Hey, this was still missing. I hope it is not too exhausting to verify this kind of changes, but I think this really improves the readability and will also help me in a later stage, when I try to merge more stuff.

[djc]

Thanks! Ideally in the future we make it so that groups that depend on some other group come before that other group (so astring and nstring should probably come before string).