Rename the Client class

[Jericho]

I regret my choice of name for the Client class. I would prefer a more descriptive name such as StrongGridClient.

Rather than simply rename the existing class and break existing code for all developers, I intend to introduce a new class called StrongGridClient and mark the old Client class as obsolete. This will allow developers some time to transition to the new name. The obsolete class will be eventually removed in a future release.