Only log issues/failures when something's actually up.
It has irked me for a long time that so much output came
out of running the tests, this seems to silence it.
It does hide some warnings, but I think it makes the output
so much more readable that it's worth the tradeoff.
Helps for highly parallel running of jobs, sometimes they'd not give output for a while.
Setting this timeout higher appears to help.
Not completely sure if this is the right place to do it, but it works fine for me.
By moving the tests subdirectory to t, we gain the ability to run `yath
test` with no arguments from inside `nix develop` in the root of the
the repo.
(`nix develop` is necessary in order to set the proper env vars for
`yath` to find our test libraries.)