Persist the datadir after option reset

After a reset is performed, the datadir setting is saved and readded to the settings so that it is persisted across option resets.

src/qt/optionsmodel.cpp

@@ -16,6 +16,7 @@
 #include "main.h" // For DEFAULT_SCRIPTCHECK_THREADS
 #include "net.h"
 #include "txdb.h" // for -dbcache defaults
+#include "intro.h" 
 
 #ifdef ENABLE_WALLET
 #include "wallet/wallet.h"
@@ -98,6 +99,9 @@ void OptionsModel::Init(bool resetSettings)
     if (!SoftSetArg("-par", settings.value("nThreadsScriptVerif").toString().toStdString()))
         addOverriddenOption("-par");
 
+    if (!settings.contains("strDataDir"))
+        settings.setValue("strDataDir", Intro::getDefaultDataDirectory());
+
     // Wallet
 #ifdef ENABLE_WALLET
     if (!settings.contains("bSpendZeroConfChange"))
@@ -150,9 +154,16 @@ void OptionsModel::Reset()
 {
     QSettings settings;
 
+    // Save the strDataDir setting
+    QString dataDir = Intro::getDefaultDataDirectory();
+    dataDir = settings.value("strDataDir", dataDir).toString();
+
     // Remove all entries from our QSettings object
     settings.clear();
 
+    // Set strDataDir
+    settings.setValue("strDataDir", dataDir);
+
     // default setting for OptionsModel::StartAtStartup - disabled
     if (GUIUtil::GetStartOnSystemStartup())
         GUIUtil::SetStartOnSystemStartup(false);