Deck.Slice is now GetCards, is private; new public Draw method; updated tests for new signatures
Updated Deck.GetCards to use Where() before Take(), so Where actually works
Added CardDrawnMarksCardAsPlayed
Deck.Draw() tests
Deck tests now have regions
Deck() w/o args no longer stupidly calls other constructor
Deck now has AllPlayed property
DeckDrawReturnsOnlyUnplayed no longer has a magic number
Deck draw tests moved to own file, DeckDrawTests.cs
Deck allPlayed field now m_allPlayed to distinguish it; Shuffle() now sets AllPlayed to false