Update Heraldo de Aragon
Do not use editor.is_modified for anything other than saving
Add actions to close editor tabs
Update Kobo firmware version. AGAIN.

Kobo are updating the firmware a lot faster than in the past. The latest
is 3.1.0. The supported version is being set to 3.1.5 in case any bug
fix only versions are released.

Also, commented out a couple of debug lines to reduce the clutter when
testing.

Fixes #1257143 [Update to support Kobo firmware 3.1.0](https://bugs.launchpad.net/calibre/+bug/1257143)
Shortcuts config, commit open editor if user clicks OK
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Start work on image editor
Refactor selection state tracking into its own class
Signal to notify when selection state changes
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Update Pocket
Use a grab cursor when moving selection rect
Turn off anti-aliasing when drawing the selection rects
Get rid of the saved message.
Table of Contents Editor: Handle generating ToC from headings if the first heading level in the document is not h1 or the document skips some intermediate heading levels
Fix handling of mouse release events during selection
A dialog to trim images
Use keypresses for fine adjustment of selection rect
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