changelog:
-reworked fuel and fire game mechanic: the fuel amount of a boiler is now hard coded from 0 to +max units, depending on the boiler size of the locomotive
one piece of firewood adds 10 fuel units
as fuel burns away, the fire particle effect starts to decrease and disappears completely once all fuel is burnt
the more fuel is in the firebox the faster the fire temperature increases; once all fuel is burnt the fire temperature starts to decrease at a constant rate until it hits 0
the higher the fire temperature the faster the water temperature increases; once the fire temperature is zero the water temperature starts to decrease at a constant rate until it hits 0

-added tutorial for RAILROADS Online! in written form for all languages: press H to open up the tutorial which helps you to get started in RAILROADS Online! You can rebind the key to open the tutorial in options->controls

-UI whistle slider will return to idle position when released