Implement new (optional) save game format

[Solen1985]

While CivOne will always be able to load and save original Civilization games, there will be an option to turn off compatibility and use a new save game format. This is needed in order to support upcoming expanded features, like:

• Larger maps
• Mod support (new units/advances/buildings)
• Removing unit/city limit
• Playing games with more than 7 civilizations

[uHappyLogic]

Please assign this task to me

[Solen1985]

@uHappyLogic If you have any ideas on the new save format, can you post them here?

[uHappyLogic]

Json will be new game save base format. New game save mode will be at first optional (enabled in configuration). Every game object which contains state will be serialized/deserialized into json object. This approach requires some changes in existing codebase and will be implemented in few stages. Additionally new mechanism will able to be used by plugins.