Book Polishing (#639)

* Downgraded ExCSS, the new version has a regression that breaks toCss().

* Cleaned up the next/prev disabling to work more reliably.

Fixed an issue with double arrow on next not disappearing after hitting last page then going back one page.

* Cleaned up some css padding on the side nav progress bar

* Remove the ability to save

* Updated colors of nav bar and side drawer to be darker to separate them from the reader

* Fixed a missed element

* Removed dead code

* Removed TODO, it can't be changed

* Refactored bookmarking on the book progress to have pinpoint accuracy for remembering scroll position. Now will choose the top line on the page.

* Fixed a style issue when applying dark mode from light mode in book reader

API/Services/ImageService.cs

@@ -46,9 +46,7 @@ namespace API.Services
 
       var firstImage = _directoryService.GetFilesWithExtension(directory, Parser.Parser.ImageFileExtensions)
         .OrderBy(f => f, new NaturalSortComparer()).FirstOrDefault();
-
-
-
+      
       return firstImage;
     }