Autotag optimisation (#2368)

* Add duration to autotag finish message
* No sorting scene/image/gallery where not specified
* Use an LRU cache for sqlite regexp function
* Compile path separator regex once
* Cache objects with single letter first names
* Move finished auto-tag log
* Add more verbose logging
* Add new changelog

pkg/sqlite/gallery.go

@@ -486,16 +486,13 @@ func galleryAverageResolutionCriterionHandler(qb *galleryQueryBuilder, resolutio
 }
 
 func (qb *galleryQueryBuilder) getGallerySort(findFilter *models.FindFilterType) string {
-	var sort string
-	var direction string
-	if findFilter == nil {
-		sort = "path"
-		direction = "ASC"
-	} else {
-		sort = findFilter.GetSort("path")
-		direction = findFilter.GetDirection()
+	if findFilter == nil || findFilter.Sort == nil || *findFilter.Sort == "" {
+		return ""
 	}
 
+	sort := findFilter.GetSort("path")
+	direction := findFilter.GetDirection()
+
 	switch sort {
 	case "images_count":
 		return getCountSort(galleryTable, galleriesImagesTable, galleryIDColumn, direction)