allow a request to be processed in a job

Now we allow a request to be passed into a job queue,
and after the job finishes the request is passed into
a controller again. In order to achieve this we have
a requests queue in System, when we put a request
to the job this Request structure is preserved in the
queue and for a new request a new Request is added to
the queue.

while here:
- remove App::Lock()/Unlock(), use scoped locking
- fix: Plugin now has a Call method which takes ModelConnector
  and a logger (used in multithreaded environment)
- BaseThread has a main_model_connector pointer
  to the main (from the main thread) model connector
- the FastCGI structure fcgi_request moved from App to Request
- some methods for handling requests moved from App to Request
- small refactoring in main.cpp
- add Http class (a http client)

winixd/core/sessioncontainer.cpp

@@ -5,7 +5,7 @@
  */
 
 /* 
- * Copyright (c) 2008-2018, Tomasz Sowa
+ * Copyright (c) 2008-2022, Tomasz Sowa
  * All rights reserved.
  * 
  * Redistribution and use in source and binary forms, with or without
@@ -82,7 +82,7 @@ Table::iterator i = table.begin();
 	{
 		if( i->plugin_data.HasAllocatedData() )
 		{
-			plugin->Call(&*i, WINIX_PLUGIN_SESSION_DATA_REMOVE); // the session passed here is ok?
+			plugin->Call(model_connector, &log, &*i, nullptr, nullptr, WINIX_PLUGIN_SESSION_DATA_REMOVE, nullptr, nullptr, 0, 0); // the session passed here is ok?
 		}
 
 		//i->plugin_data.DeleteAll(); // it's better to call it here instead in the destructor
@@ -116,7 +116,7 @@ IndexId::iterator i = index_id.find(id);
 
 		if( i->second->plugin_data.HasAllocatedData() )
 		{
-			plugin->Call(&*(i->second), WINIX_PLUGIN_SESSION_DATA_REMOVE); // the session passed here is ok?
+			plugin->Call(model_connector, &log, &*(i->second), nullptr, nullptr, WINIX_PLUGIN_SESSION_DATA_REMOVE, nullptr, nullptr, 0, 0); // the session passed here is ok?
 		}
 
 		//i->second->plugin_data.DeleteAll();