settings file and save/restore ui state

src/settings.h

@@ -0,0 +1,35 @@
+#pragma once
+#include "serializer.h"
+
+class Settings : public Serializer::Descriptor
+{
+public:
+    Settings() { class_id = "pref"; }
+    static Settings I;
+    static bool load();
+    static bool save();
+    static bool has(const std::string& key)
+    {
+        return I.Descriptor::has(key);
+    }
+    template <typename T> 
+    static void set(const std::string& key, const T value)
+    {
+        I.Descriptor::set(key, value);
+    }
+    template <typename T>
+    static std::shared_ptr<T> get(const std::string& key)
+    {
+        return I.Descriptor::get<T>(key);
+    }
+    template <typename T, typename D = decltype(T::value)>
+    static void value(const std::string& key, D& dest)
+    {
+        I.Descriptor::value<T, D>(key, dest);
+    }
+    template <typename T>
+    static auto value(const std::string& key)
+    {
+        return I.Descriptor::value<T>(key);
+    }
+};