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/pluginmsg.h

@@ -5,7 +5,7 @@
  */
 
 /* 
- * Copyright (c) 2008-2021, Tomasz Sowa
+ * Copyright (c) 2008-2022, Tomasz Sowa
  * All rights reserved.
  * 
  * Redistribution and use in source and binary forms, with or without
@@ -180,6 +180,7 @@ namespace Winix
 
 // the request is being ended
 // you can clear some of your objects here
+// in p1 you have a pointer to the Request object
 #define WINIX_END_REQUEST					30140
 
 // a new file (page) has been added
@@ -323,6 +324,13 @@ namespace Winix
 // session is null
 // if you process the job then return 'true' from the processing method (from plugin call)
 // so this prevent to make a standard (system) job
+// in l1 there is a job type (from JobTask structure), e.g. if you want to know whether
+// the job is a request continuation you should compare l1 == JobTask::JOB_TYPE_REQUEST_CONTINUATION
+// in l2 there is a job_id - the values passed to the Job::Add(long job_id, ...) method
+// if you have called Add(...) without long job_id parameter then the default value JobTask::JOB_ID_DEFAULT is used
+// if the job type is JobTask::JOB_TYPE_REQUEST_CONTINUATION then a pointer to Session can be set,
+// such a Session has allow_to_delete flag set to false but of course you have to Lock/Unlock when
+// you are using this structure
 #define WINIX_JOB							31200