Edit book: Insert tag button: Allow entering attributes along with the tag name to make it easy to repeatedly insert, for example, <span class="special"></span>.
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Edit Book: Allow putting the editor into replace mode by pressing the Insert key
Edit Book: When refreshing the ToC view pick up the unsaved changes, if any, in the ncx file
Edit Book: Update the Table of Contents view automatically when the ncx file is edited.

Also avoid unnecessary rebuilds of the Table of Contents view.
Ignore errors during live refresh of the toc view
E-book viewer: When using the tap and hold gesture on a touchscreen, allow lookup  of the word currently under the finger in the dictionary or online. Fixes #1318242 [Enhancement: allow text select on Windows Tablet, perhaps with stylus](https://bugs.launchpad.net/calibre/+bug/1318242)
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Make word under cursor detection more robust
Change the demo link in the README.md

The demo link (https://calibre-ebook.com/demo) present in the README.md threw a certificate error. This modification makes the URL use the HTTP protocol to avoid this issue.
Merge branch 'patch-1' of https://github.com/aymericbeaumet/calibre
Fixed a libimobiledevice resource leak.
Better logo resolution
Merge branch 'patch-1' of https://github.com/sylvaindurand/calibre
Merge branch 'master' of https://github.com/GRiker/calibre
Add a note about how the beautify algorithm works.
Highlighting groups for spell check
Store language data when syntax highlighting
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Function to return the number of utf-16 code points in a python string on wide python builds