add deleteCards methods

[mac-gallagher]

• Replaced deleteCard:atIndex and deleteCard:atPosition with deleteCards:atIndices and deleteCards:atPositions methods
• Add swipedCards -> [Int] method

Closes #103

[codecov-commenter]

Codecov Report

Merging #109 into master will increase coverage by 0.3%.
The diff coverage is 100.0%.

@@           Coverage Diff            @@
##           master    #109     +/-   ##
========================================
+ Coverage    84.4%   84.8%   +0.3%     
========================================
  Files          13      13             
  Lines         740     759     +19     
========================================
+ Hits          625     644     +19     
  Misses        115     115             

Impacted Files	Coverage Δ
...Shuffle/SwipeCardStack/CardStackStateManager.swift	100.0% <100.0%> (ø)
...ources/Shuffle/SwipeCardStack/SwipeCardStack.swift	100.0% <100.0%> (ø)