Refactoring for Cleanliness and Support for Client

* Added Corporation.toString
* Added Tile.getName and Tile.toString
* Modified Board.getAdjacentCorporations to accept a Tile instead of row,
  col
* Modified Deck.getStock, Deck.getRemaining, Deck.getSortedStockHolders,
  and Deck.draw to accept Corporations instead of corpNums
* Modified MessageSender.placeTileMsg to use Tile instead of row, col
* Modified MessageSender.tskMsg to use Corporation instead of corpNum
* Modified MessageSender.sbMsg to use Lists instead of arrays
* Added MessageSender.turnMsg and removed turnPlayerNum from
* MessageSender.endTurnMsg
* Removed playerNum from MessageSender.killedMsg
* Added MessageSender.tskPromptMsg
* Added MessageHandler with common functionality to read primitives,
  Tiles, and Corporations from an input stream
* Refactored ServerMessageHandler to match changes to MessageSender
* Refactored ServerMessageHandler to extend MessageHandler and use its
  methods
* Refactored GameFlowController to match above changes