- Async loading supports cancellation through a `CancellationToken`. If loading is cancelled an `OperationCanceledException` is thrown.  If it fails for another reason a `LoadWeightsFailedException` is thrown.
 - Updated examples to use `LoadFromFileAsync`

* Added the ability to save and load individual conversations in a batched executor.
 - New example
 - Added `BatchedExecutor.Load(filepath)` method
 - Added `Conversation.Save(filepath)` method
 - Added new (currently internal) `SaveState`/`LoadState` methods in LLamaContext which can stash some extra binary data in the header

* Added ability to save/load a `Conversation` to an in-memory state, instead of to file.

* Moved the new save/load methods out to an extension class specifically for the batched executor.

* Removed unnecessary spaces