Make it so users do not accidentally create empty NSError objects as those can crash applications when returned to Objective-C for processing.

Objective-C code expects NSError objects to be properly initialized when returned.
In too many cases users return NSError objects that were created with the default
constructor which really should not take place.

We are making this Obsolete as we should remove this in future versions.   There is
only one mild case where you can use this object and it is when passing to Objective-C
methods that will initialize and poke at the internals of an NSError themselves, but
these are rare.
bring xamarin's master in synch with mono's maccore/master
Provide NSUrl bindings where previously we only had CFUrl
Expose the underlying error code when throwing exceptions and only use the initialized guard to prevent the slow startup lookups, not to enforce its use
Ensure we generate unique names for selectors (e.g. when one ends with ':'). Fix bug #2626
Fix names for manually used selectors inside monotouch.dll
Fix merge conflict
ios6: NSAttributedString changes
Add NSUUid
ios6: Add NSINdexPath methods
ios6: new enum values for new PKCS supported SHA formats
ios6: the one CoreAnimation update
Add NSValue methods that box MKCoordinateSpan and CLLocationCoordinate2D objects
MapKit: NSValue properties to fetch the Coordinate and the CoordinateSpan
ios6: Small CoreImage updates
Merge branch 'master' into ios6
Add ios6 api
avfoundation: ios6 classes
ios6: NSTextAlignment is not shared between MonoMac and MonoTouch, they will live in different namespaces
Fix ObsoleteAttribute output for properties (it was attached to private field)