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Fix #1341232 [minor additional update to ScienceDaily recipe](https://bugs.launchpad.net/calibre/+bug/1341232)
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Nicer layout for Tag Browser panel in Preferences
Edit Book: When right clicking on a link add a menu entry to open the link
Fix #1341240 [zsh-completion silently fails to install](https://bugs.launchpad.net/calibre/+bug/1341240)
Edit Book: Add in-context help for HTML and CSS

Now, you can right click on any HTML/OPF/NCX tag name or CSS property
and the editor will open some help for that item in your browser.
Port compiling of .ui forms
Port imports
Port build script for building PyQt extensions to PyQt5
Port the progress indicator extension to PyQt5
Allow controlling PyQt5 import path via the env var PYQT5_IMPORT_PATH
faster builds
Get rid of the PyQt4 string from everywhere
Port: setMargin() reset() QStringList()

setMargin(): QLayout no longer has a setMargin() function, replace with
setContentsMargins()

reset(): QAbstractListModel no longer has reset(), replace with
beginResetModel(), endResetModel()

QStringList: No longer exists, a simply python list of strings works
instead
Fix mouse wheel not working in diff view
Port coffeescript compiler
Add note about headless Qt QPA plugin
Port WebKit imports and QChar

WebKit has been split up into QtWebKit and QtWebKitWidgets. Change
imports accordingly.

Replace use of QChar since it no longer exists in PyQt5
Port syntax highlighters