Replace last occurrences of PropertyEditor by EditorInspector

Updates the following plugins:
- ConnectionsDialog
- ScriptEditorDebugger
- ItemListEditorPlugin

Also drop now unnecessary compatibility methods.

editor/script_editor_debugger.h

@@ -33,12 +33,12 @@
 
 #include "core/io/packet_peer.h"
 #include "core/io/tcp_server.h"
-#include "property_editor.h"
+#include "editor/editor_inspector.h"
+#include "editor/property_editor.h"
 #include "scene/gui/box_container.h"
 #include "scene/gui/button.h"
 
 class Tree;
-class PropertyEditor;
 class EditorNode;
 class ScriptEditorDebuggerVariables;
 class LineEdit;
@@ -130,7 +130,7 @@ class ScriptEditorDebugger : public Control {
 	LineEdit *vmem_total;
 
 	Tree *stack_dump;
-	PropertyEditor *inspector;
+	EditorInspector *inspector;
 
 	Ref<TCP_Server> server;
 	Ref<StreamPeerTCP> connection;