Modified Steam Locomotive Steam/Smoke code to pulse the steam, producing a better stack effect.
Commented out Line 279, Alerter Update from version 1972 which causes any key press with a Steam Locomotive to crash the game.
git-svn-id: http://svn.uktrainsim.com/svn/openrails/trunk@1973 a9f3cfff-6c41-7446-b0ca-052bd761e6eb