Ability to delete authorization keys added.

If we start logging in and we know, that some of the authorization
keys were read from the hard drive, not generated, we destroy all
the existing authorization keys and start generating new keys.

Telegram/SourceFiles/intro/introphone.cpp

@@ -30,6 +30,7 @@ Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
 #include "ui/effects/widget_fade_wrap.h"
 #include "core/click_handler_types.h"
 #include "boxes/confirmbox.h"
+#include "messenger.h"
 
 namespace Intro {
 
@@ -57,6 +58,8 @@ PhoneWidget::PhoneWidget(QWidget *parent, Widget::Data *data) : Step(parent, dat
 		_country->onChooseCountry(qsl("US"));
 	}
 	_changed = false;
+
+	Messenger::Instance().destroyStaleAuthorizationKeys();
 }
 
 void PhoneWidget::resizeEvent(QResizeEvent *e) {