~~ MASSIVE rewrite of the ICancellableEnumerable stuff worked, and now is IAsyncAction (and friends)
~~ ctrl-c is much more responsive when cancelling an operation. Still more to be done here.
~~ IAsyncValue<T> and IAsyncEnumerable are really cool.
~~ NuGet/Chocolatey -- changed usage of the PackageRepository to now use the IQueryable via our own IEnumerable<> implementation. Net result - WAY FASTER.
~~ Many Code Cleanups
~~ folded the Provider Services directly into the request object.
~~ Duck Typer works around IDisposable (without accidentally calling the Original Dispose() when the DuckType'd instance's Dispose is called)
~~ Removed superflous Should* from HostApi
~~ added support for Magic Signatures in Provider model. Now we can quickly skip a provider examining a file
~~ added support to check for supported uri schemes in providers
~~ Fixed Downloaders and Archivers to use same pattern for SupportedSchemes and MagicSignatures
~~ renamed RequestImpl to IRequestObject
~~ Refactored ReEnumerable and BlockingCollection to share base class MutatableEnumerable.
~~ Fixed List<T,T2> 's implementation of Contains().  Stupid equals operator.
~~ Replaced Parallel.ForEach with ParallelForEach extension Method.
~~ lots of tweaks to NuGet/Chocolatey
~~ Added -Tag support for NuGet/Chocolatey