Fix podofo 0.9.3 faillilng with test file

Use a slightly different test file
Implement v2 codesigning for the calibre app bundle on OS X

calibre is now built on 10.9.5 as that is the only version of OS X that
supports v2 codesigning. v2 codesigning is required for Gatekeeper on
all versions of OSX >= 10.9.5
Edit metadata dialog: Allow undoing a metadata download by long-clicking the Download metadata button and choosing "Undo last metadata download"
Update regex module from upstream
List of current Qt 5workarounds that are obsoleted by Qt 5 bug fixes
Also undo cover download
Fix a bug that prevented post-import file type plugins from being run when adding books via the GUI
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Fix a regression in 2.3 that broke creation of collections on the device when metadata management was set to manual. Fixes #1371976 [Not writing Collection data to sony prs-350](https://bugs.launchpad.net/calibre/+bug/1371976)
pep8
Edit metadata dialog: Allow undoing the changes to individual fields by right clicking on the field and selecting Undo after a metadata download. Fixes #1223367 [Feature Request: Don't "destroy" undo/ctrl-z and redo/ctrl-y for the fields, after metadata download](https://bugs.launchpad.net/calibre/+bug/1223367)
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Some debugging for the History stack
Clear history when opening new book
Fix file internal links having different effect on history as compared to links that cause a new file to be loaded
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Fix #1367992 [Losing History in the eBook Viewer](https://bugs.launchpad.net/calibre/+bug/1367992)
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