Edit Book: Fix an error when running the Check Book tool on files with empty <style> tags. Fixes #1320459 [Private bug](https://bugs.launchpad.net/calibre/+bug/1320459)
Add .ibook*s* as a recognized ebook format as well
Start work on Live CSS view
Dont show an error message when trying to use quick open with no book open
Update Instapaper
Preview panel: Improve robustness of resource loading from the book

Ensure that resources are always loaded from the current container, even
if the current container was changed since the base URL was specified.
While this is unlikely to happen, it is best to be robust.
Implement code to retrieve style information for the Live CSS panel
Handle media queries when finding matching CSS rules
Update Slate
Only return first matching selector, instead of the full selector text
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Allow calibre to be used by multiple users on Mac OS X.

Fixes bug #1320347

For reference see https://developer.apple.com/library/ios/documentation/General/Reference/InfoPlistKeyReference/Articles/LaunchServicesKeys.html#//apple_ref/doc/uid/20001431-113300
OS X Build: Fix a bug that was preventing multiple instances of calibre being used by different user accounts on the same computer. Fixes #1320347 [Multiple users cannot run Calibre concurrently](https://bugs.launchpad.net/calibre/+bug/1320347)

Merge branch 'fanf/multiuser' of https://github.com/fanf2/calibre
Edit book: Fix Check Book failing if a binary file such as an image or font is mislabelled in the OPF as being a text file. Fixes #1320977 [Private bug](https://bugs.launchpad.net/calibre/+bug/1320977)
Docs for the set semantics tool
Live CSS renders
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Implement collapsing of live css groups
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