Use libadblockplus update checker

src/plugin/PluginUpdateDialog.h

-// CUpdateDialog
-
-class CUpdateDialog : public CAxDialogImpl<CUpdateDialog>
-{
-
-public:
-
-  CUpdateDialog()
-  {
-  }
-
-  ~CUpdateDialog()
-  {
-  }
-
-  enum { IDD = IDD_UPDATEDIALOG };
-
-  BEGIN_MSG_MAP(CUpdateDialog)
-    MESSAGE_HANDLER(WM_INITDIALOG, OnInitDialog)
-    COMMAND_HANDLER(IDOK, BN_CLICKED, OnClickedOK)
-    COMMAND_HANDLER(IDCANCEL, BN_CLICKED, OnClickedCancel)
-    CHAIN_MSG_MAP(CAxDialogImpl<CUpdateDialog>)
-  END_MSG_MAP()
-
-  // Handler prototypes:
-  LRESULT OnInitDialog(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled);
-  void SetVersions(CString new_version_, CString cur_version);
-  LRESULT OnClickedOK(WORD wNotifyCode, WORD wID, HWND hWndCtl, BOOL& bHandled)
-  {
-    EndDialog(wID);
-    return 0;
-  }
-
-  LRESULT OnClickedCancel(WORD wNotifyCode, WORD wID, HWND hWndCtl, BOOL& bHandled)
-  {
-    EndDialog(wID);
-    return 1;
-  }
-
-private:
-
-  CString m_curVersion;
-  CString m_newVersion;
-};