-Fix: For everyone who tried to crash the game by opening a huge amount of windows and stickying all of them; bad luck. It's fixed now (thanks Tron for the helpful criticism). First all normal windows are a candidate for replacement, then if none are found, sticky windows. Then..well that should not happen :)
This adds a little button per vehicle class to the station window which opens a list of all vehicles that have this station on their schedule.
As side effect this gets rid of some global variables.
-Fix: Sorter icon pointing down 'v' sorts in every window lowest value first, '^' highest value first
-CodeChange: move Dropdownlist from settings_gui.c to widget.c. More in place there.