Enhance the random map generation

[WGierke]

• [x] Allow saving of seed to restore the map
• [x] Add back loading of a pre-designed map as an alternative to generated one
• [x] Add a camera that follows the first car, so we can generate endless tracks.

[WGierke]

Saving the map seed has been added in fa164bad54700656f7c957fec02a8c9bf0c19cab

[sleighsoft]

@Raandom Can you do that part with the camera until next week?

[sleighsoft]

@Raandom Can this be closed?