New features
Browser viewer: Allow customizing what information is displayed in the header and footer areas. Access Preferences from the viewer controls to change.
Add support for MTP devices on FreeBSD
ToC editor: Add more case changing operations to the right click menu
Content server: Redirect pre 2.x book URLs to new 3.x URLs via a JavaScript redirect
Content server: Allow opening entries in the book list in a new tab via middle click/right click
Add a tweak in Preferences->Tweaks to exclude some fields when using the Edit metadata->Copy/paste actions
Linux: Allow using calibre-tray.png in the calibre resources folder to override the system tray icon.
Closes tickets: 1738518
Bug fixes
Browser viewer: Fix goto next/previous section actions not working when the sections are in different individual HTML files.
Closes tickets: 1740333
Edit book/Book polishing: When compressing images and the compressed image is larger thant he original, use the original image.
Closes tickets: 1741063
PDF input: Fix conversion of multi-level PDF Outline causing duplicate entries in the Table of Contents.
Closes tickets: 1738385
Edit book: Fix incorrect EPUB 3 declarations being added to the OPF file when adding covers to an EPUB 2 book
Edit book: Fix backspace key un-indenting instead of deleting even when text is selected if the cursor is at the start of the line
Tag browser: Fix position not bing preserved when deleting books.
Closes tickets: 1740387
Edit Book: Use the cache directory rather than the temp directory to store working files. Hopefully prevents temp file cleaners from destroying books.
Closes tickets: 1740460
EPUB input: Handle books that erroneously set the mimetype for font files to text/plain
AZW3 input: Do not fail to process files with invalid internal flow references.
Closes tickets: 1740140
When updating plugins, do not show the dialog asking which toolbar to put the plugin, even if the user has removed the plugin for all toolbars.
Content server: Fix using the Clear logs button preventing the server from restarting until calibre itself is restarted.
Closes tickets: 1738433
Improved news sources
LA Times
Popular Science
Nikkei News
http://calibre-ebook.com/