This does many meta-things, but changes no functionality:
 - get rid of stack, and use just cabal with a stackage snapshot instead
   (why did I ever think stack was a good idea?)
 - update the stackage snapshot to something halfway recent
 - thus making builds work on nixpkgs-23.05 (current stable)
 - separating out packages into their own cabal files
 - use the GHC2021 set of extensions as default
 - very slight code changes to make things build again
 - update readme accordingly
 - stylish-haskell run

(also got rid of the map templater, which had version problems with
mustache — it's not likely anyone will need it anyways)

this removes:
 - the bbb properties
 - all explicit mentions of rc3
 - the weird script domain hacks (done via a substitution now)
 - some (few) of the weirder code choices

it also adds some more type level witchery to deal with configs, which
for some reason seems to be the hardest problem of this entire program …

also the server now does inter-assembly dependency checking!

also don't keep adjusted maps around if not necessary

(instead, `walint --version` will now just say "unknown")

as annoying as yaml is, cabal's package format is somehow worse, apparently

If --version is given, `walint` prints version information, then exists
with code 0.

(and no one's documented that)

Anyways it now uses utf8 which seems a little more reasonable.