PyGtk compatibility fixes for RHEL 6.1 + variants (closes bgo#691738)
Fix regression from commit e03492 (closes bgo#693856)
Fix regression from 2d9c99 (closes bgo#693986)
Fix overzealous inline highlighting invalidation (closes bgo#693690)

In the existing code, any buffer change invalidated all pending inline
highlighting jobs. This causes serious issues if any highlighting jobs
are pending when a change is made; these jobs will never be restarted
unless their chunks are directly changed.

The solution in this patch is to only consider inline highlighting
results to be invalid if the actual text being highlighted has changed.
We do this by using gtk.TextMarks instead of gtk.TextIters (avoiding
buffer invalidation) and checking to see whether the text we're about
to highlight actually matches what we think we're highlighting. If it
doesn't, then we have a changed block, which *will* be rehighlighted
in the relevant changed callback.

The downside to this approach is that creation of gtk.TextMarks and
validating the text before highlighting is computationally much more
expensive than our previous approach.
Updated Czech translation
Updated Polish translation
Updated Serbian translation
Fix VC comparison for non-VC folders
Update NEWS
Pre-release version bump
Fix pygtk 2.16 incompatiblity
Updated Slovenian translation
Fix initialisation of translations under Windows
Fix support for 'threaded' diff by using threads on Windows

Rather than try to make this code multiprocessing-safe on Windows, this
patch just moves to using a thread pool on Windows, and move code
around to make this cleaner.
Avoid some GTK+ warnings by ensuring a style is set on required widgets
PEP8 fixes for matchers
Add CONFLICT types and get_path_for_conflict methods to bzr and git
Add kwargs to create-diff signal and use to specify merge output
Open conflicted files in a 3 way auto merge.
Mark merge descriptors for translation