Allow searching for tags in the device view. Works for books on the device that came from calibre or have matched a calibre book in the past.
Don't search tags when the expression is unprefixed. Some performance improvements and defensive code.
Device view: Allow searching the tags of books that match books in the calibre library by prefix the search term with tags:
EPUB Output: Fix splitting of large HTML files removing all child tags from inside <pre> tags. Fixes #1267327 [Private bug](https://bugs.launchpad.net/calibre/+bug/1267327)
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HTML Input: Fix UTF-16/32 encoded files that are linked to from the parent file not being properly processed. Fixes #1268262 [convert html file encoded as utf-16 fail to include image files and have wrong order](https://bugs.launchpad.net/calibre/+bug/1268262)
Update NY Times some more
Refactor dialog base class into its own module for easier re-use
Merge branch 'master' of https://github.com/kovidgoyal/calibre