CommonReactiveSource allows section info list to be updated.

Note that now we require at least IReadOnlyList instead of
just IEnumerable.  I argue that this is the morally correct
thing to do since it allows us to ditch .ToList().
Reactive{Collection,Table}ViewSource now are IReactiveNotifyPropertyChanged.

Uses copy-paste from ReactiveNSView.
Stronger-typed CommonReactiveSource.
New Data property for Reactive{Collection,Table}ViewSource.
CommonReactiveSource now reacts to section changes.
Fix a couple of boring bugs.
Oh, snap!
New extension methods for Reactive{Collection,Table}ViewSources.
Do not try to automagically convert strings to NSStrings.

IMHO this is the morally correct action to take.  iOS is going
to compare strings by reference, so:

  - Original code by @paulcbetts used a cast from string to
    NSString.  I have no idea how it works, but it does seem hackish.

  - I had modified the code to use new NSString(), which in
    hindsight obviously will not work.

  - This new version does not autoconvert anything at all, thus
    the process is transparent and does not rely on internal details.
Observable for single property, which doesn't query the value if skipInitial is true (useful for F#)
Merge remote-tracking branch 'origin/pr/403'
Merge remote-tracking branch 'origin/pr/402'
What's this silly goosery
Remove bogus XML doc genning from RxUI.Events MonoMac