Improved management of online status from non-primary windows.

– The online status of the user should be checked and updated only
when the previous active window and the current active window both have
different sessions.
– Removed MainWindow::activeChangedHook since windows should not
change online status on their own on activating.
– Renamed Application::maybeActiveSession
to Application::maybePrimarySession.
– Added updating of online status on changing of the current account
since this seems to have been missed.

Telegram/SourceFiles/window/window_controller.cpp

@@ -123,6 +123,8 @@ void Controller::showAccount(
 			}, _sessionController->lifetime());
 
 			widget()->setInnerFocus();
+
+			session->updates().updateOnline(crl::now());
 		} else {
 			setupIntro();
 			_widget.updateGlobalMenu();