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, 7 insertions, 2 deletions

diff --git a/MediaBrowser.Controller/Entities/Extensions.cs b/MediaBrowser.Controller/Entities/Extensions.cs
index f3bddd29c..d2ca11740 100644
--- a/MediaBrowser.Controller/Entities/Extensions.cs
+++ b/MediaBrowser.Controller/Entities/Extensions.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Linq;
+using MediaBrowser.Common.Extensions;
 using MediaBrowser.Model.Entities;
 
 namespace MediaBrowser.Controller.Entities
@@ -28,13 +29,17 @@ namespace MediaBrowser.Controller.Entities
                     Url = url
                 };
 
-                if (item.RemoteTrailers.Length == 0)
+                if (item.RemoteTrailers.Count == 0)
                 {
                     item.RemoteTrailers = new[] { mediaUrl };
                 }
                 else
                 {
-                    item.RemoteTrailers = item.RemoteTrailers.Concat(new[] { mediaUrl }).ToArray();
+                    var oldIds = item.RemoteTrailers;
+                    var newIds = new MediaUrl[oldIds.Count + 1];
+                    oldIds.CopyTo(newIds);
+                    newIds[oldIds.Count] = mediaUrl;
+                    item.RemoteTrailers = newIds;
                 }
             }
         }