allow user to register BmpToAvi

Cool idea, but unnecessary: now that the installer correctly handles upgrading (each release must have a new project GUID, but the same upgrade GUID), this situation can't arise anymore.

if (bta.GetLastError() == CBmpToAvi::ERR_CREATE_SOURCE
&& hr == REGDB_E_CLASSNOTREG) {
    static const LPCSTR BmpToAviName = "BmpToAvi.ax";
    if (AfxMessageBox(IDS_MEX_BTA_INSTALL, MB_YESNO) == IDYES) {
        CPathStr    path = CMainFrame::GetAppPath();
        path.Append(BmpToAviName);
        if (PathFileExists(path)) {
            CString cmd;
            cmd.Format("regsvr32 /s \"%s\"", path);
            int retc = system(cmd);
            if (retc)
                AfxMessageBox(IDS_MEX_BTA_CANT_REG);
            else
                goto retry;
        } else {
            CString s;
            s.Format(IDS_MEX_BTA_NOT_FOUND, BmpToAviName);
            AfxMessageBox(s);
        }
    }
}