Automapping strategies

[jagregory]

Rewrite the automapper to allow substitutable behaviour.

The automapper currently uses a bunch of "setup" funcs that define how it behaves; however, this isn't very flexible as it's only capable of working in the set few ways we allow it to.

Rewrite the automapping internals to use a strategy that can be passed in by the user (or a default implementation provided by us).

AutoMap.AssemblyOf<X>()
  .WithStrategy(new MyCustomAutomappingStrategy());