OTP : Improve : tighten the security + cosmetic

set double authentication : create, send link, usable with
FreeOTP (opensource) AEgis (opensource) and Google Authenticator

1. OTP : prevent direct access without going throught the 2FA mechanism
2. Go back to the url where you were disconnected
3. Cosmetic

html/export.php

@@ -49,6 +49,12 @@ $gDossier=dossier::id();
 $g_parameter=new Noalyss_Parameter_Folder($cn);
 mb_internal_encoding("UTF-8");
 $g_user->Check();
+/**
+ * check if 2FA is completed
+ */
+if ( ! $g_user->is_double_identified()) {
+   exit();
+}
 $action=$g_user->check_dossier($gDossier);
 
 $hi=new HttpInput();