Properly handle SynchronizatonContext

[murshex]

:)

[MarkCiliaVincenti]

Thank you for your contribution :)

Can you carry out these changes please?

1. There is no need to create new methods; just use the existing ones and add the parameter with a default value of false.
2. Please change the summary description to: "true to attempt to marshal the continuation back to the original context captured; otherwise, false. Defaults to false."

[murshex]

Modified as per request of Mr. Vincenti

[MarkCiliaVincenti]

Thank you! I'll release as beta until this new functionality is covered by tests.