The requests time out for some reason but at least we're trying something.

Also sketch out a demo program

we need to use an _even older_ version of ghc than we're using now and
modern-uri doesn't seem particularly amenable to that.

network-uri is perfectly fine, anyway.

quite possibly both of these interfaces are wrong
may want to ponder them for a moment before proceeding

Simplistic implementation of download

Closes #1

See merge request !1

And it only tells us what cabal tells us later, packages are broken...

fresh start

reduce closure size etc

Tell cabal to configure zlib a certain way when building it, making its build
errors go away without changing our own cabal package configuration.

`cabal list-bins ...` might output some garbage before outputting the path, so
this breaks :/  Also why do it the hard way when we can do it the easy way!