Add CSFML dependency + nix-shell

shell.nix

@@ -3,11 +3,19 @@
 with pkgs;
 
 let
+  mycsfml = csfml.overrideAttrs (oldAttrs: rec {
+    src = fetchFromGitHub {
+      owner = "lafeychine";
+      repo  = "CSFML";
+      rev   = "d4deb5e3360dafd9f56a569c004a74ff02a56d7d";
+      sha256 = "sha256-64NcpW1aDvH5SfGVjfU3J/m2r7Oi0NlFYlDShHODZGE=";
+    };
+  });
   llvmPackages = llvmPackages_13;
   stdenv = llvmPackages.libcxxStdenv;
 in stdenv.mkDerivation (rec {
   name = "prog-2";
-  buildInputs = [ llvmPackages.lld sbt SDL2 which ];
+  buildInputs = [ mycsfml llvmPackages.lld sbt which ];
   LD_LIBRARY_PATH =
-    lib.makeLibraryPath [ llvmPackages.libcxx llvmPackages.libcxxabi SDL2 ];
+    lib.makeLibraryPath [ mycsfml llvmPackages.libcxx llvmPackages.libcxxabi ];
 })