Edit Book: When editing EPUB files, and a file is added in META-INF/ do not automatically add it to the manifest. Also do not warn about unmanifested files inside META-INF/ since a few vendors (Apple) require non standard files in that location. Fixes #1283015 [com.apple.ibooks.display-options.xml](https://bugs.launchpad.net/calibre/+bug/1283015)