Explore route in activity mode

When this mode is selected, an activity is automatically generated from the parameters defined by the player in the main menu window. This way the player may explore the route in autopilot mode and with random weather effects, etc.. Also signals, speed limits and so on are managed in activity mode.

Discussion: http://www.elvastower.com/forums/index.php?/topic/31135-autopilot-to-explore-route/
Roadmap: https://trello.com/c/zXyIcw8K/342-explore-route-in-activity-mode