Edit-book: After removing CSS file the program should also remove all references to that file from HTML files
Steps to reproduce bug:
1) Open to edit pub file with CSS file referenced to HTML files.
2) Remove that CSS file from EPUB file.
Edit-book should also remove all references from HTML files. Fox example:
Warning [7 / 37]
The resource pointed to by this link does not exist. You should either fix, or remove the link.