"Pullee mode" ("jazda ciągniona") for vehicles

[jakubg1]

A new flag should be added to vehicles, called "pullee mode". This is especially important now since it is currently impossible to have an inert vehicle in the consist that has a spring brake - the spring brake will be turned on and the train will not achieve high speeds.

Pullee mode turns all security systems off and releases the brakes.

Additionally, cabs of some locomotives have a switch which could be activated after adding this mode.