Reduce graph: added option to remove orphan nodes from WM after reduction (#1735)

* Reduce graph: remove orphan nodes from WM after reduction

* fixed eror

* ignore ids< 0

* add warning and cleanup only when option is used

* updated feedback

* Abort --sync_wm_and_opt_graph if a lot more WM nodes have to be transferred.

* typo

* refactored... completly

* fixed optimized graph cleared

* updated option description

* updated comment

* Added dummy dictionary function to speedup initialization when we dont need the dictionary fully loaded in memory.

* Fixed nodes weight not modified in db when deleted

* Removed AutoUpdate parameter, not needed

* Fixed dummy dictionary usage for detectMoreLoopClosures. Added checks to disable graph reduction when intermediate nodes are detected.

* updated log

corelib/src/Rtabmap.cpp

@@ -180,7 +180,8 @@ Rtabmap::Rtabmap() :
 	_pathGoalIndex(0),
 	_pathTransformToGoal(Transform::getIdentity()),
 	_pathStuckCount(0),
-	_pathStuckDistance(0.0f)
+	_pathStuckDistance(0.0f),
+	_dummyDictionary(false)
 #ifdef RTABMAP_PYTHON
 	,_python(new PythonInterface())
 #endif
@@ -360,6 +361,10 @@ void Rtabmap::init(const ParametersMap & parameters, const std::string & databas
 	if(!_memory)
 	{
 		_memory = new Memory(allParameters);
+		if(_dummyDictionary)
+		{
+			_memory->setDummyDictionary(true);
+		}
 		_memory->init(_databasePath, false, allParameters, true);
 	}
 
@@ -6934,6 +6939,18 @@ void Rtabmap::addNodesToRepublish(const std::vector<int> & ids)
 	}
 }
 
+void Rtabmap::setDummyDictionary(bool enabled)
+{
+	if(_memory) {
+		UERROR("Memory is already initialized, cannot set dummy dictionary. This "
+			"function can only be called after Rtabmap object is created, but "
+			"before init() is called.");
+	}
+	else {
+		_dummyDictionary = true;
+	}
+}
+
 void Rtabmap::clearPath(int status)
 {
 	UINFO("status=%d", status);