Edit book: When showing HTML tag mismatch errors, show clickable links for the opening as well as the closing tags
Edit book: Add various validity checks for OPF files.

Check for incorrect idrefs, missing required sections, non-linear items
in the spine.
...
Check for duplicate items in the manifest
...
Check for entries in the manifest that point to missing files
Check for duplicates in the spine
Fix #1269592 [Edit Book: New unreleased Manifest missing files test is buggy](https://bugs.launchpad.net/calibre/+bug/1269592)
...
...
Add tests for invalid pointer to toc in <spine>
...
Prevent setting an incorrect value for compression quality in the wireless driver causing an error

Show a busy cursor while calibre is working on matching books on the
device to books int he library, which can take a while if the user has a
lot of books on the device.

Merge branch 'master' of https://github.com/cbhaley/calibre
Initial import of Patience Diff C implementation from bzr
Get the patience diff module compiling and loading