j: 902-release-b -> 904-beta-c
j: 902-release-b -> 904-beta-c

An almost complete rewrite was made. Now the detection of main features are made
by Nix code, emulating the detection of upstream source scripts.

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs