move all expressions to nix/; include modularized home-manager config

nix/home-manager/programs/homeshick.nix

@@ -0,0 +1,38 @@
+{ pkgs
+, config
+, ...
+}:
+
+let 
+  bootstrapRepos = pkgs.writeScript "bootstrapRepos" ''
+    set -e
+    echo home-manager path is ${config.home.path}
+    echo home is $HOME
+
+    source ${pkgs.homeshick}/homeshick.sh
+    type homeshick
+      
+    # echo Updating homeshick
+    # ln -sfT ${pkgs.homeshick} "$HOMESICK_REPOS"/.homeshick
+    # mv -Tf "$HOMESICK_REPOS"/{.,}homeshick
+    '';
+
+in {
+  home.sessionVariables = {
+    HOMESHICK_DIR="${pkgs.homeshick}";
+  };
+
+  home.activation.bootstrapRepos = config.lib.dag.entryAfter ["writeBoundary"] ''
+    $DRY_RUN_CMD ${bootstrapRepos}
+  '';
+
+  nixpkgs.config = {
+
+    packageOverrides = pkgs: with pkgs; {
+      homeshick = builtins.fetchGit {
+        url = "https://github.com/andsens/homeshick.git";
+        ref = "master";
+      };
+    };
+  };
+}