1.0.0-beta.13

• Removed the StreamContent content provider in favor of the new MemoryContent content provider (should also provide a nice performance boost since there's no more stream locking).
• Added IExecutionContext.GetContentProvider() extensions that take a byte[] buffer.
• Added new MemoryContent content provider that wraps a byte[] buffer.
• Changed IEngine.Settings to be mutable, settings can now be added directly to the engine after instantiation.
• Fixed a bug with case-insensitive settings from the command line.
• Fixed a bug with computed metadata settings from the command line.