Fix EditorFileSystem duplicating root folder in new folders

Also, add some uninitialized variables into constructors (I like to applease cppcheck).
Also, remove unused md_count.
Fixes #3662.

(cherry picked from commit c89d9720f0bd3fa46cb812c110ba3534ca169567)

editor/editor_file_system.cpp

@@ -207,6 +207,7 @@ EditorFileSystemDirectory::EditorFileSystemDirectory() {
 
 	modified_time = 0;
 	parent = NULL;
+	verified = false;
 }
 
 EditorFileSystemDirectory::~EditorFileSystemDirectory() {
@@ -1038,7 +1039,10 @@ bool EditorFileSystem::_find_file(const String &p_file, EditorFileSystemDirector
 		if (idx == -1) {
 			//does not exist, create i guess?
 			EditorFileSystemDirectory *efsd = memnew(EditorFileSystemDirectory);
+
 			efsd->name = path[i];
+			efsd->parent = fs;
+
 			int idx2 = 0;
 			for (int j = 0; j < fs->get_subdir_count(); j++) {
 
@@ -1252,6 +1256,7 @@ EditorFileSystem::EditorFileSystem() {
 
 	singleton = this;
 	filesystem = memnew(EditorFileSystemDirectory); //like, empty
+	filesystem->parent = NULL;
 
 	thread = NULL;
 	scanning = false;
@@ -1259,7 +1264,9 @@ EditorFileSystem::EditorFileSystem() {
 	thread_sources = NULL;
 	new_filesystem = NULL;
 
+	abort_scan = false;
 	scanning_sources = false;
+	scanning_sources_done = false;
 	ResourceSaver::set_save_callback(_resource_saved);
 
 	List<String> extensionsl;

editor/editor_file_system.h

@@ -193,8 +193,6 @@ class EditorFileSystem : public Node {
 
 	void _scan_fs_changes(EditorFileSystemDirectory *p_dir, const ScanProgress &p_progress);
 
-	int md_count;
-
 	Set<String> valid_extensions;
 
 	void _scan_new_dir(EditorFileSystemDirectory *p_dir, DirAccess *da, const ScanProgress &p_progress);