Support property changes in derived collections

Adds support for updating derived collections when items in the source
collection changes (INPC). Changes to source items can result in items
being added to or removed from the derived collection as well as items
changing places (due to new sort conditions).

In order to make this possible I've moved all of the synchronization logic
into the RDC class itself and the class has been split into two parts. The
RDC<T> class is exposed to callers of CreateDerivedCollection (for
backwards compatibility and sanity) and RDC<TSource,TValue> which contains
the magic ingredient TSource (the type of the source collection items).

In order to support all scenarios of value and reference types, orderers
and no orderers filters and what not RDC now maintains a map between the
item indices and their corresponding indices in the source collection
allowing it to track and map changes in the origin collection to their
projected counterparts regardless of type and value/reference type
changes.

Also supports items existing in multiple places in the source collection
whether or not the selector is an identity function or if they're mapped
to value types.

This is a breaking change for the following reasons:
  * RDC constructor no longer accepts an IDisposable
  * RDC is now explicitly read only (modifying a derived collection makes
    no sense and now it's enforced. All modifying methods throws and the
    IsReadOnly property is set to true.

TODO:
  * CreateCollection is currently broken. I don't think it will be hard to
    fix it but I want to get some feedback on this change first.
  * One possible performance optimization would be to maintain an inverse
    map of source indices to destination indices which would allow for
    quicker lookups. Needs to be measured and weighed against increase
    complexity. Could also enable binary search for reverse lookup.
  * Another possible perf gain is to use binary search for
    positionForNewItem.
Getting rid of awkward reset overload

ReactiveDerivedCollection needs to override the implementation of Reset
while still being able to use SuppressChangeNotification. My previous
hack to allow this needs to be killed with fire so I'm adding
publishResetNotification to ReactiveCollection. It's not ideal but at
least it's better than the previous version.
Proper IDisposable implementation for RDC
Remove unused method param, consolidate methods
Renaming internalInsert, removing unused method
Make the strongly typed Add method virtual
Make RDC base class readonly

Move all throwing read-only methods into RDC<T> and expose internal
read/write methods to implementing classes.
Re-enable CreateCollection

Moving logic into internal helper class based on
ReactiveDerivedCollection<T>.
Typo
Reformat to fit in < 120 chars
Make RDC private fields read only
Avoid potentially wasteful compare call
Adhere to coding conventions
Fix up RxColl test
Simplify unit test detection and design mode detection.

Remove old platform directives.
Move UnitTestDetector and DesignModeDetector to their own files.