module: add wm

This module sets up window managers, and the common xorg configuration
between them.

modules/modules/desktop/wm.nix

@@ -0,0 +1,46 @@
+{ pkgs, lib, config, ... }:
+with lib;
+with lib.hlissner;
+let
+  cfg = config.modules.desktop.wm;
+in
+{
+  options.modules.desktop.wm = {
+    enable = mkBoolOpt false;
+    qtile.enable = mkBoolOpt false;
+  };
+
+  config = mkIf cfg.enable (mkMerge [
+    {
+      info = {
+        graphical = mkDefault true;
+        monitors = mkDefault 1;
+      };
+
+      services.xserver = {
+        enable = true;
+        displayManager.lightdm.enable = true;
+      };
+
+      environment.systemPackages = with pkgs; flatten [
+        (with xorg; [
+          xwininfo
+          xprop
+        ])
+
+        xsecurelock
+        blugon
+      ];
+    }
+    (mkIf cfg.qtile.enable {
+      services.xserver.windowManager.qtile.enable = true;
+
+      info.env.wm = "qtile";
+
+      fonts.fonts = with pkgs; [
+        powerline-fonts
+        ubuntu_font_family
+      ];
+    })
+  ]);
+}