Remove lots of dead code. Refactor IOHandler, GameElement.

+ Remove dead alpha-beta code in MinimaxPlayer.
+ Remove GameTree.Node class. Nodes in a GameTree are
  also GameTrees. Remove unused methods from GameTree.
+ Add MockTerminalView and MockGameController classes.
  Remove multi-arity methods with boolean "pause" flags.
  Refactor tests to use new mock objects.
+ Refactor IOHandler: now an Interface with just one method.
  Remove unused Console wrapper methods.
+ Refactor CharStreamConsole and SystemConsole to implement
  IOHanlder interface. Extract both to standalone classes.
+ Remove bubbled exceptions in method signatures. Replace
  with localized exception handling.
+ Remove InvalidPlayerException.
+ Remove Column and Diagonal class.
+ Remove abstract GameElement class, extract to final
  TicTacToeSymbols class with static final fields.
  X, O, _ now handled with static imports.
+ Extract TerminalView strings to properties file.
+ Attempt to add code coverage to Ant build.
Merge branch 'master' of https://github.com/ecmendenhall/Java-TTT

Pushed commit with incorrect message.