Made the selection in track drawing mode work better. It's no longer possible to accidentally try to connect to curves when not intended. Thi is something Master Hellish struggled with, so I tried to make it more intuitive.

Circular arc curve extension for track drawing preview.

Made better error message for trains that get stuck in dead ends.

Removed any possiblity of disabling vsync via config. Also, fastest sim rate used to disable vsync. If, for some reason, the framerate goes too fast despite vsync being enabled, it will be limited by a busy wait to have a min frame time of 6.5 ms (153.8 fps).

Updated button toggle states in draw function so that they are always up to date with the actual editing mode.

Made foot bridges slightly darker so they are more visible, and now they have thickness and railings.

Make pillars of track bridges not intersect tracks below.