portable windows data directory

FS.cpp

@@ -46,8 +46,18 @@ namespace fs {
     }
 #if defined(WIN32) || defined(_WIN32)
     char localAppData[MAX_PATH];
+    // check executable directory first
+    GetModuleFileName (NULL, localAppData, MAX_PATH);
+    auto execPath = boost::filesystem::path(localAppData).parent_path();
+    // if config file exists in .exe's folder use it
+    if(boost::filesystem::exists(execPath/"i2pd.conf")) // TODO: magic string
+        dataDir = execPath.string ();
+    else
+    {
+        // otherwise %appdata%
         SHGetFolderPath(NULL, CSIDL_APPDATA, 0, NULL, localAppData);
         dataDir = std::string(localAppData) + "\\" + appName;
+    }
     return;
 #elif defined(MAC_OSX)
     char *home = getenv("HOME");