Unit Tests & New Natural Sort (#941)

* Added a lot of tests

* More tests! Added a Parser.NormalizePath to normalize all paths within Kavita.

* Fixed a bug where MarkChaptersAsUnread implementation wasn't consistent between different files and lead to extra row generation for no reason.

* Added more unit tests

* Found a better implementation for Natural Sorting. Added tests and validate it works. Next commit will swap out natural Sort for new Extension.

* Replaced NaturalSortComparer with OrderByNatural.

* Drastically simplified and sped up FindFirstEntry for finding cover images in archives

* Initial fix for a epub bug where metadata defines key as absolute path but document uses a relative path. We now have a hack to correct for the epub.

API/Extensions/VolumeListExtensions.cs

@@ -12,7 +12,8 @@ namespace API.Extensions
         {
             return inBookSeries
                 ? volumes.FirstOrDefault(v => v.Chapters.Any())
-                : volumes.OrderBy(v => v.Number, new ChapterSortComparer()).FirstOrDefault(v => v.Chapters.Any());
+                : volumes.OrderBy(v => v.Number, new ChapterSortComparer())
+                    .FirstOrDefault(v => v.Chapters.Any());
         }
 
         /// <summary>