Adjacent crossings: add setting (in PATX), add info to SLXI chunk.

src/table/settings.ini

@@ -2506,6 +2506,16 @@ def      = NULL
 proc     = RedrawScreen
 cat      = SC_BASIC
 
+[SDT_BOOL]
+base     = GameSettings
+var      = vehicle.adjacent_crossings
+guiflags = SGF_NO_NETWORK
+def      = true
+str      = STR_CONFIG_SETTING_ADJACENT_CROSSINGS
+strhelp  = STR_CONFIG_SETTING_ADJACENT_CROSSINGS_HELPTEXT
+cat      = SC_BASIC
+patxname = ""adjacent_crossings.vehicle.adjacent_crossings""
+
 
 ;***************************************************************************
 ; Unsaved setting variables.