Add a method to save data of players

[Seniru]

Lots of players complained that their data have been destroyed when we run a fresh instance of the game. So it is essential to use a save function to save player data.

To improve the efficiency, following objectives are planned to achieve through this issue.

• Using system methods to save and load player data. Also planned to use DataHandler class created by the community for ease
• Caching players data after the execution of script, such that the cached data can be used to retrieve data of players

[Seniru]

Closing this issue with the commit 0b93723
The system can now save the money, level, xp, education stats, degrees, titles, current title and inventory
The system cannot save the data of current job and owned companies related to the player