This OXP demonstrates how to use the EmailSystem. In particular it shows how to create messages with callbacks, and how to re-connect those messages after a save.

It is a simple mission which runs as follows:
1. Send an email to the player that asks whether they want to play a game.
	- A "Yes" and "No" option will be available to the player.
2. If the player selects "No", another email will be sent to the player and the game is over.
3. If the player selects "Yes", another email will be sent to the player, telling them the game has started. The player needs to look at the email trace to see where the email came from. That will be the destination the player needs to travel to.
4. Once the player travels to the correct destination and docks with the main station, they will receive another email, indicating they have found the Chaser. They will then be asked whether they enjoyed the game.
	- A "Yes" and "No" option will be available to the player.
5. Another email will be sent, based on the selected response. Then the mission will end.

The game can be saved at any point without impacting on the state of the mission.

The purpose in these steps is not to demonstrate complex mission sequences, but to illustrate the following parts of the system
1. Creating standard email messages (ie. messages with no required responses)
2. Creating email messages with multiple response options.
3. How to re-establish the connection between email responses and callback functions when a game has been saved with a response pending.

