Improved:
- Minor refactoring.
- Fixed mix of System.out.println and print statements.
- Added proper way to set indentation level to print and printLua.
- method play:
  - Do not close System.in.
- method handleActionInput
  - Do not box value after parsing.
- method outputAvailableActions
  - Use ListIterator<Action> over Iterator<Action>.
- method printLua
  - Refactored it into a processLuaTable method that gets called.
Minor refactoring and using inbuilt function check of luaj which will emit a LuaError rather than the old IllegalStateException.
Updated gitignore to ignore some netbeans files.
Updated pom to always show if using deprecated features.
Added extra null checks and changed the cards zone to be of type Optional<Zone>, rather than using null for signalling absence.
Merge pull request #3 from Cardshifter/core-game-improvements

Core game improvements
Merge pull request #5 from Cardshifter/core-game

Core game improvements