Consider moving Selection and Record into a subfolder

[kevinresol]

It would be easier to navigate when they are separated from the "core" types.

[back2dos]

I think Record could stay where it is, as it's a pretty basic building block. But yeah, Selection could be moved out. Wasn't there a coconut.ds at some point?

[kevinresol]

Wasn't there a coconut.ds at some point?

It is still there. But it is basically a mess now. I don't like how they are now. I would like to make them more simplistic but I am bad at designing. I will revisit them.