Add grid view, image to tag (#641)

* Add grid view for tags
* Add tag page
* Import/export tags
* Add tag name uniqueness checks
* Fix styling on missing marker previews
* Add trace loglevel
* Add SQL trace
* Add filter options for tags
* Add tag sort by options
* Add tag page keyboard shortcuts

pkg/api/context_keys.go

@@ -11,4 +11,5 @@ const (
 	studioKey    key = 3
 	movieKey     key = 4
 	ContextUser  key = 5
+	tagKey       key = 6
 )