upper limit for train_waiting_at_signal_tick_multiplier_penalty

[Optera]

What?
Add a way for mods to set an upper limit for train_waiting_at_signal_tick_multiplier_penalty.

Why?
Currently trains waiting in a stacker can accumulate insane amounts of tick penalty.
Take a stacker for 3 trains.
Track 1 has two trains, 1 in station and 1 in stacker waiting for several minutes
Track 2 has 1 train in station

When 3 trains arrive at the stacker what happens is that Track 2 is filled with 2 trains and the 3rd train insists on going into track 2 as well instead of queuing up at Track 1 because tick penalty from the train waiting in Track 1 stacker is higher than the train_waiting_at_signal_penalty from Track 2.

In this example limiting the tick penalty to 99 would allow the 3rd train to queue up on Track 1.