new lifts and plain station for era a + bugfix

try and make train doors open on the platform side

small tweaks

unlock station squares in 1850

new larger stations and a couple of bugfixes

lotsa textures, models et al for the three eras

fix terminals along the same track

finer platform textures and fewer glitches

fix crash when joining consecutive tracks into different terminals (UG should do this)

better handling of multiple underground levels. Reconfigure your existing underground stations after this.