Don't use std::string in the plugin, convert when communicating with the engine

src/plugin/PluginUserSettings.cpp

 #include "PluginStdAfx.h"
 #include "PluginUserSettings.h"
 #include <algorithm>
 #include "PluginSettings.h"
 #include "PluginClient.h"
 #include "PluginIniFileW.h"
 
 static const CString s_GetMessage = L"GetMessage";
 static const CString s_GetLanguageCount = L"GetLanguageCount";
 static const CString s_GetLanguageByIndex = L"GetLanguageByIndex";
@@ skipping 257 matching lines @@
       pVarResult->bstrVal = SysAllocString(url);
     }
   }
   else if (s_GetWhitelistDomains == method)
   {
     if (pDispparams->cArgs)
       return DISP_E_BADPARAMCOUNT;
 
     if (pVarResult)
     {
-      std::vector<std::string> whiteList = settings->GetWhiteListedDomainList();
+      std::vector<std::wstring> whiteList = settings->GetWhiteListedDomainList();
       CString sWhiteList;
       for (size_t i = 0; i < whiteList.size(); i++)
       {
         if (!sWhiteList.IsEmpty())
         {
           sWhiteList += ',';
         }
-        sWhiteList += CString(CA2W(whiteList[i].c_str(), CP_UTF8));
+        sWhiteList += CString(whiteList[i].c_str());
       }
 
       pVarResult->vt = VT_BSTR;
       pVarResult->bstrVal = SysAllocString(sWhiteList);
     }
   }
   else if (s_AddWhitelistDomain == method)
   {
     if (1 != pDispparams->cArgs)
       return DISP_E_BADPARAMCOUNT;
@@ skipping 20 matching lines @@
     {
       settings->RemoveWhiteListedDomain((BSTR)domain);
     }
   }
   else
     return DISP_E_MEMBERNOTFOUND;
 
   return S_OK;
 }