Basic configuration file init and ppm value save/load test

src/AppConfig.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <wx/stdpaths.h>
+#include <wx/dir.h>
+#include <wx/filename.h>
+
+#include "DataTree.h"
+
+class AppConfig {
+public:
+
+    std::string getConfigDir();
+
+    void setPPM(std::string device_serial, int ppm);
+    int getPPM(std::string device_serial);
+    bool save();
+    bool load();
+    bool reset();
+private:
+    std::map<std::string, int> device_ppm;
+};