gitit: init at 0.13.0.0

This was broken in `haskellPackages` for a long time, but it’s back!

Time to give it a place in the toplevel and a prope) treatment:

* Semi-static binary
* Remove all references to `Paths_` modules of dependencies
* gitit tries very hard to have a runtime dependency on GHC, disable
  that by default.

Also added myself as a maintainer, let’s try to keep this working from
now on.

Fixes https://github.com/NixOS/nixpkgs/issues/32377

pkgs/development/tools/pandoc/default.nix

@@ -10,8 +10,8 @@ in
     buildTools = (drv.buildTools or []) ++ [ removeReferencesTo ];
   })).overrideAttrs (drv: {
 
-    # These libraries are still referenced, because pandoc references
-    # their `Paths_*` module for figuring out their version.
+    # These libraries are still referenced, because they generate
+    # a `Paths_*` module for figuring out their version.
     # The `Paths_*` module is generated by Cabal, and contains the
     # version, but also paths to e.g. the data directories, which
     # lead to a transitive runtime dependency on the whole GHC distribution.