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/plugins/export/init.cpp

@@ -5,7 +5,7 @@
  */
 
 /* 
- * Copyright (c) 2011-2021, Tomasz Sowa
+ * Copyright (c) 2011-2022, Tomasz Sowa
  * All rights reserved.
  * 
  * Redistribution and use in source and binary forms, with or without
@@ -251,12 +251,12 @@ void Init(PluginInfo & info)
 {
 using namespace Export;
 
-	info.set_dependency_for(edb);
+	edb.set_dependency(info.functions);
 	edb.SetConn(info.db->GetConn());
 	edb.LogQueries(info.config->log_db_query);
 	edb.SetDirs(&info.system->dirs);
 
-	info.set_dependency_for(export_info);
+	export_info.set_dependency((WinixModelDeprecated*)info.functions);
 	export_info.SetSystem(info.system);
 	export_info.SetConfig(info.config);
 	export_info.SetEDb(&edb);