Edit book: Allow linking of stylesheets into HTML files automatically.  Right click ont he selected HTML files in the File browser and choose "Link stylesheets" to have the <link> tags for the shhets automatically inserted.
Edit book: Automatic correction of font family names not quoting family names with spaces in them if the original, incorrect family name did not have a space. Fixes #1263448 [Problem with css auto-correct in editor](https://bugs.launchpad.net/calibre/+bug/1263448)