Fix warnings, improve performance (#1665)

* Fix warnings, improve performance

`QueryResult.Items` is now a `IReadOnlyList` so we don't need to
allocate a new `Array` when we have a `List` (and `Items` shouldn't need to
be mutable anyway)

* Update Providers .csproj to latest C#

* Remove extra newline from DtoService.cs

* Remove extra newline from UserLibraryService.cs

1 files changed, 9 insertions, 9 deletions

diff --git a/MediaBrowser.Controller/Entities/Folder.cs b/MediaBrowser.Controller/Entities/Folder.cs
index d841b7ef8..d61a07066 100644
--- a/MediaBrowser.Controller/Entities/Folder.cs
+++ b/MediaBrowser.Controller/Entities/Folder.cs
@@ -666,36 +666,36 @@ namespace MediaBrowser.Controller.Entities
             query.StartIndex = null;
             query.Limit = null;
 
-            var itemsList = LibraryManager.GetItemList(query);
+            IEnumerable<BaseItem> itemsList = LibraryManager.GetItemList(query);
             var user = query.User;
 
             if (user != null)
             {
                 // needed for boxsets
-                itemsList = itemsList.Where(i => i.IsVisibleStandalone(query.User)).ToList();
+                itemsList = itemsList.Where(i => i.IsVisibleStandalone(query.User));
             }
 
-            BaseItem[] returnItems;
+            IEnumerable<BaseItem> returnItems;
             int totalCount = 0;
 
             if (query.EnableTotalRecordCount)
             {
-                var itemsArray = itemsList.ToArray();
-                totalCount = itemsArray.Length;
-                returnItems = itemsArray;
+                var itemArray = itemsList.ToArray();
+                totalCount = itemArray.Length;
+                returnItems = itemArray;
             }
             else
             {
-                returnItems = itemsList.ToArray();
+                returnItems = itemsList;
             }
 
             if (limit.HasValue)
             {
-                returnItems = returnItems.Skip(startIndex ?? 0).Take(limit.Value).ToArray();
+                returnItems = returnItems.Skip(startIndex ?? 0).Take(limit.Value);
             }
             else if (startIndex.HasValue)
             {
-                returnItems = returnItems.Skip(startIndex.Value).ToArray();
+                returnItems = returnItems.Skip(startIndex.Value);
             }
 
             return new QueryResult<BaseItem>