Refactor toolbar creation code for eventual user customizability
Edit Book: Allow customization of toolbars
Refactor the code to embed metadata into format files to enable re-use
RTF metadata: Add proper support for unicode characters when reading and writing metadata to RTF files

Also fix failure to write metadata to RTF files that do not already have
a \info block
New tool to set metadata in the actual book files in the calibre library from the updated metadata in the calibre database. To use it go to Preferences->Toolbars and add the "Embed metadata" tool to the main toolbar. Then simply select the books whose files you want to update and click the Embed metadata button. Normally, calibre updated metadata in the book files whenever a file is exported from calibre. This tool is useful for people who want the files int he calibre library to have updated metadata as well.
calibredb: Add a new 'embed_metadata' command to update metadata in the actual book files in the calibre library from the calibre database.
version 1.41.0
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Edit Book: Remove unused CSS: Fix an erro if an HTML file links to a missing stylesheet
Edit Book: Spell check dialog: Add an option to make filtering the word list case sensitive
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Partial fix for check book with epub files with non-ascii internal filenames on os x
Edit Book: Fix various problems when editing EPUB files with non-ascii filenames on OS X. Fixes #1317883 [calibre should care of 'decomposed UTF-8' filenames on Darwin platform](https://bugs.launchpad.net/calibre/+bug/1317883)
Edit Book: When editing HTML files that have charset encoding declarations, automatically change the declared encoding (if any) to UTF-8 on save, since the editor always saves files in the UTF-8 encoding.

This prevents a mismatch between the declared encoding and the actual
encoding if the HTML file was originally in an encoding other than
UTF-8.
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Edit Book: Check Book: Add a check for HTML files with non UTF-8 encoding declarations
Refactor html syntax highlighting and implement profiling
Edit Book: 2x speedup for inline spell checking. Useful if you are editing large HTML files (over 100KB in size).

Qt's text layout engine becomes very slow if we store arbitrary python
objects in QTextCharFormat classes. So refactor to not do that.