Modularize and improve mail and calendar config

home/programs/khal/default.nix

@@ -0,0 +1,26 @@
+{ config, ... }:
+{
+  programs.khal = {
+    enable = true;
+    locale = {
+      timeformat = "%H:%M";
+      dateformat = "%m-%d";
+    };
+  };
+
+  accounts.calendar.accounts = {
+    "radicale" = {
+      khal = {
+        enable = true;
+        type = "discover";
+        color = "light blue";
+      };
+    };
+    "university" = {
+      khal = {
+        enable = true;
+        color = "#c72125";
+      };
+    };
+  };
+}