Fix #1360547 ["Legacy" window title](https://bugs.launchpad.net/calibre/+bug/1360547)
Fix the unified title and toolbar on Mac tweak causing calibre to fail to work because of a bug in PyQt5
Workaround for Qt 5 bug that prevents using the return key to edit table cells in the main book list

https://bugreports.qt-project.org/browse/QTBUG-40938
E-book viewer: Fix navigating to a bookmark not updating the displayed page number. Fixes #1360621 [(ebook-viewer) weird behaviour dealing with current page in ePub](https://bugs.launchpad.net/calibre/+bug/1360621)
Linux: Disable the optional system tray icon in linux because of bugs in the system tray icon implementation in Qt 5 on linux. See #1360652 (calibre 2.0 system tray icon missing, cannot quit)

https://bugreports.qt-project.org/browse/QTBUG-31762
pep8
Prevent calibre from installing or running on Windows XP as there have been many reports of Qt 5 crashing on Windows XP and Windows XP is now no longer supported by Microsoft.
Possible fix for --detach crash on some linux systems

Do not use file objects for redirecting the std streams as they could be
garbage collected closing the streams. Also redirect stdin. I dont
really expect either of these to fix the issue, but it's a start.
Use C code to redirect standard I/O streams for --detach and --daemonize
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Fix regression in calibre 2.0 that caused crashes when using drag and drop to re-order virtual library tabs
ebook-viewer: Handle --open-at using a localized string (, instead of .  for decimal separator)
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Add translatable strings from the QT font dialog
pep8
Fix calibre not using system color scheme

Apparently on windows and OS X if the application style is set before
the application object is constructed the system color scheme is not
read.
Merge branch 'master' of https://github.com/cbhaley/calibre
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